Abstract

The NEPOMUK Calendaring Ontology intends to provide vocabulary for describing calendaring data (events, tasks, journal entries) which is an important part of the body of information usually stored on a desktop. It is an adaptation of the ICALTZD ontology created by the W3C RDF Calendar Task Force of the Semantic Web Interest Group in the Semantic Web Activity. This document describes the reasons behind the adaptation, the changes performed, as well as an overview of the classes and properties of the NCAL ontology.

Status of this document

This document arose from the work of the Task-Force ontologies within the NEPOMUK project. This document is a DRAFT made available by the Nepomuk Consortium for discussion only. This document is a work in progress and may be updated, replaced, or rendered obsolete by other documents at any time.

This document is a part in a set of seven documents, which together comprise the complete specification of the Nepomuk Information Element Ontology Framework. These are: NIE, NFO, NCO, NMO, NCAL, NEXIF, NID3.

Ontology Visualisation

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  • Contents

    1. Introduction
    1.1 Previous work
    2. Drawbacks of the ICALTZD ontology
    2.1 Underspecification
    2.1.1 Property values and parameters
    2.1.2 Domains of calendar properties
    2.1.3 Missing Entity Types
    2.1.4 No limited vocabulary
    2.1.5 Vague semantics of the component property
    2.2 Errors
    2.3 Ranges of datatype properties
    2.4 Design decisions unacceptable in Nepomuk
    2.4.1 OWL
    2.4.2 Timezones as datatypes
    2.5 Alignment with contact ontology
    3. NCAL Development process
    4. Differences between NCAL and ICALTZD
    4.1 Timezones
    4.2 Alignment with NCO
    4.3 Union Classes
    5. Known limitations of NCAL
    6. Future versions
    7. Examples

    1. Introduction

    Nepomuk Calendar Ontology (NCAL) has been designed to describe various entries usually found in calendars. These include events, tasks (todo's) and journal entries. It is an adaptation of the well known iCalendar specification published in 2002 as RFC 2445 [RFC2445]. This section begins with an outline of the previous attempts in adapting RFC 2445 to RDF. It gives an account of the issues with existing ICAL ontologies that make them unusable within Nepomuk. Following subsections describe the process adopted for the creation of NCAL and it's result - the classes and properties of the ontology. Proposed solutions to problems found in existing ICAL ontologies are presented. At the end, a list of known limitations of NCAL is given, followed by ideas for future work on improving NCAL.

    The following sections make use of the vocabulary specified in RFC 2445. The reader is advised to get acquainted with it before continuing reading. A nice outline of the structure of iCalendar specification can be found in [TIMBLICAL].

    1.1 Previous work

    The need for a common vocabulary for describing calendaring information in RDF has been recognized early within the W3C RDF Interest Group. Organized activity has been started on 9th of October 2002 at the SWAD-Europe Workshop on the Semantic web and Calendaring in Bristol, UK. The report from this workshop [SWAD37] mentions earlier attempts by Tim Berners-Lee ([TIMBLICAL]), Arick and Miller ([HYBRIDICAL]) and Dan Connoly ([ANOTHERICAL],[PALMICAL]).

    Work continued through a series of meetings. Numerous discussions were held using the www-rdf-calendar@w3.org mailing list. The archive is available at here and the #rdfig channel on the Freenode IRC network. Logs of these discussions are available here.

    After three years of research the group has produced two ontologies in OWL and a W3C Interest Group Note ([ICALNOTE]) describing the design decisions that have been made. The first ontology, hosted under http://www.w3.org/2002/12/cal/ical is more popular, semantic web enthusiasts try to publish their calendars with this vocabulary, even though the creators themselves have abandoned it in favour of a newer one, hosted under http://www.w3.org/2002/12/cal/icaltzd. The main difference between these two lies in treatment of timezones. Many entities in the iCalendar data model contain various dates and times. They are usually accompanied by a timezone that should serve as a context to interpret them. The older ontology represents this fact with a 'tzid' property more in-line with the original representation. The newer one uses a controversial approach of representing the timezones as datatypes for literals.

    In the rest of this section the older ontology will be referred to as ICAL ontology, whereas the newer one will be called the ICALTZD ontology to avoid confusion. TZD stands for ``TimeZones as Datatypes''. Whenever concrete properties from the ICAL ontology are referred, they will be given with the 'ical' prefix (e.g. ical:attendee). ICALTZD properties will use the 'icaltzd' prefix (e.g. icaltzd:component).

    2. Drawbacks of the ICALTZD ontology

    ICALTZD ontology is newer and better developed. Therefore it was chosen to serve as a the model for NCAL. Numerous drawbacks have been identified in it though. This section gives an account of them. It is intended to provide justification for the decision not to use ICALTZD directly.

    Most of the deficiencies of ICALTZD have been caused by the automatic process of its creation. It is automatically generated from the text of the RFC itself using a combination of a python script and an XSLT transformation. (Refer to [ICALNOTE] for details). This process overlooks many details that cannot be extracted with a simple analysis of the structure of the document. They would require deeper understanding of the text itself, which is certainly beyond the capabilities of such simple tools. Following subsections explain four kinds of problems encountered when trying to use ICALTZD within Nepomuk: underspecification, bugs, superfluous elements and pieces of design that certainly cannot be considered errors in themselves but are nevertheless against the guidelines for NIE.

    2.1 Underspecification

    ICALTZD is underspecified. There are many places, where certain structural information is not explicitly stated within the ontology. The user needs to be aware of the 'conventions' adopted by the authors.

    2.1.1 Property values and parameters

    RFC 2445 specifies a generic model where each calendar property can be adorned with any number of parameters. Some properties (e.g. UID) don't accept any parameters. These can easily be modelled in RDF. Their ranges can be set to appropriate XML Schema datatypes. Other properties (e.g. Attendee) accept a number of parameters. They cannot be easily modelled in RDF because literals cannot serve as subjects of RDF triples. An intermediary node is necessary.

    Using intermediary nodes to express property values poses two problems. The first one being the type of that node. ICALTZD uses untyped blank nodes for this purpose. This is against the recomendations for using property domains and ranges within Nepomuk Representational Language (See [NRLSPEC] sec. 2.3.1). The Closed-World assumption adopted in NRL implies that domains and ranges are constrains that must be met. Untyped resources cannot be related in NRL.

    Whenever such intermediary blank nodes are used as property values, the ICALTZD ontology doesn't specify the ranges of those properties at all. (e.g. in icaltzd:attach, icaltzd:dtend, icaltzd:dtstart, icaltzd:due, icaltzd:duration, icaltzd:exdate, icaltzd:exdate, icaltzd:rdate, icaltzd:recurrenceId, icaltzd:trigger, icaltzd:tzurl, icaltzd:url). It is worth noting that in some cases the ICALTZD ontology simplifies the model defined in RFC 2445 and discards some parameters. This happens for instance in 8 properties that use parameters for alternate representation (ALTREP) and language (LANGUAGE) namely: icaltzd:comment, icaltzd:description, icaltzd:location, icaltzd:resources, icaltzd:summary and icaltzd:contact. These simplifications are not documented anywhere. They can only be learned by observing the example files provided with the ontology.

    An attempt has been made to develop a utility that would convert raw iCalendar files to an RDF representation conforming to the ICALTZD ontology. It was developed as an element of the Aperture Framework. Due to the underspecification of properties the developers had to document the conventions by themselves. Each property has been characterised with following attributes:

    The last of those four characteristics is especially important since it constitutes the second of those two problems mentioned above. RFC 2445 allows for a property to have multiple value types. The actual type is indicated by a special parameter (VALUE). It is difficult to model this behavior in a general case. ICALTZD makes no attempt to formalize it and forces to user to learn the conventions expressed in examples.

    Property parameters are modelled in ICALTZD as rdf properties with no domains and ranges specified at all. Because of that each parameter can just as well be applied to any property. The same applies to parameters of recurrence rules (RRULE and EXRULE property values). Their usage must be learned from the RFC 2445 or from the example files. The ontology itself contains too little information.

    2.1.2 Domains of calendar properties

    RFC 2445 specifies four properties that apply directly to the central Vcalendar object. These are icaltzd: prodid, icaltzd: calscale, icaltzd: method and icaltzd: version. They don't have their domain specified at all.

    2.1.3 Missing Entity Types

    As said before many properties that accept parameters deserve to have a special classes as their ranges. From these four deserve to be mentioned separately. They are different from other structured values because they are described with their own vocabulary i.e. not with 'normal' ical parameters as defined in sec. 4.2 of RFC 2445.

    RFC 2445 defines the concept of a timezone observance. Each timezone can have two observances - daylight and standard. This models a common practice to use different time in the winter and in the summer. Properties responsible for this in the ICALTZD ontology are icaltzd:daylight and icaltzd:standard. They don't have their ranges specified, even though RFC 2445 treats them as separate subcomponents within the timezone component. They are marked with a separate pair of BEGIN and END constructs. The ontology makes no provision for it being a separate class.

    A similar situation occurs with recurrence rules i.e. values of RRULE and EXRULE properties. They define patterns for the repetition of a calendar event. ICALTZD doesn't mention them specifically. They are expressed as untyped blank nodes. Recurrence rule properties are attached to untyped blank nodes.

    There are also two properties that don't accept any parameters, but their values are structured. That is a comma separated value of the GEO property, which signifies coordinates of a point, and a semicolon-separated value of the REQUEST-STATUS property.

    2.1.4 No limited vocabulary

    Many properties and parameters defined in RFC 2445 (e.g. CLASS, STATUS, TRANSP, PARTSTAT, RELTYPE etc.) have a limited set of values. This is not expressed in the ICALTZD ontology. The user needs to learn those acceptable values by him- or herself in order to generate RDF that can be exported to a valid iCalendar file.

    2.1.5 Vague semantics of the component property

    ICALTZD defines an icaltzd: component property to link the calendar with the components it contains. It is also used to link the events with their alarms but even though Timezone Observances also have their own BEGIN and END constructs, the icaltzd:component property is not used there. These usage patterns have been extracted from the example files provided by the authors of the ICALTZD ontology. The ontology itself doesn't define any domain or range for the icaltzd:component property.

    2.2 Errors

    Two problems have been identified when working with the ICALTZD ontology. The first one concerns the domain of the icaltzd:rrule property. It is defined as an anonymous owl union class.

    <rdf:Description rdf:ID="rrule">
    <rdfs:domain>
    <owl:Class rdf:nodeID="DomainOf_rrule">
    ....
    </owl:Class>
    <rdfs:domain>
    ...
    </rdf:Description>

    We see that the nodeID construct has been used. This means an identifier of a blank node. This might not have been the intention of the author though since two other properties icaltzd:recurrenceId and icaltzd:exdate refer to it, but they do it wrong.

    <rdf:Description rdf:ID="recurrenceId">
    <rdfs:domain>
    <owl:Class rdf:about="#DomainOf_rrule"/>
    </rdfs:domain>
    </rdf:Description>

    This construct refers to an URI, not to a blank node. The W3C RDF validator interprets the first example as:

    subject: http://www.w3.org/2002/12/cal/icaltzd#rrule
    predicate: http://www.w3.org/2000/01/rdf-schema#domain
    object: genid:UDomainOf_rrule

    Whereas the second example is interpreted as:

    subject: http://www.w3.org/2002/12/cal/icaltzd#recurrenceId
    predicate: http://www.w3.org/2000/01/rdf-schema#domain
    object: http://www.w3.org/2002/12/cal/icaltzd#DomainOf_rrule

    Which is clearly not the same.

    The second problem with ICALTZD are multiply defined ID's. The W3C RDF Validator finds 53 redefinitions of a previously defined identifiers. This fact has caused problems when working with the RIO 1.0 RDF Parser. It could potentially cause problems with other tools, even though semantically it makes no difference if a statement occurs once or multiple times within an RDF document.

    There are also repetitions in OWL unions that describe the domains of properties.

    2.3 Ranges of datatype properties

    An attempt has been made to model the datatypes of literals that serve as property values. A set of datatypes has been defined. These include icaltzd: Value_DATE-TIME, icaltzd: Value_CAL-ADDRESS, icaltzd: Value_PERIOD, icaltzd: Value_RECUR etc. They have been defined as rdfs: Datatype but there are no additional characteristics of them. In most cases they can safely be expressed with either xml schema datatypes or special-purpose classes. It is worth noting that the datatype for dates and times is defined twice: as icaltzd: Value_DATE-TIME and icaltzd: dateTime.

    2.4 Design decisions unacceptable in Nepomuk

    2.4.1 OWL

    The most important fact, that inhibits the usability of ICALTZD within Nepomuk is that it is expressed in OWL. This violates the guideline expressed here. Even though OWL classes and properties could theoretically be interpreted as RDFS constructs, ICALTZD makes use of OWL unions, which have no equivalent in RDFS.

    2.4.2 Timezones as datatypes

    A second design decision that may be considered controversial is the timezones-as-datatypes idea. Whenever point in time is referenced it is described with a date, time and a timezone. The first two parts can be expressed with a single literal, formatted according to the XML Schema 'dateTime' format. The timezone though is expressed as the datatype of that literal. Example files provided with the ICALTZD ontology contain many entries similar to the following one:

    <Vevent rdf:about="#D4F0202E-2F2F-11D7-A96C-000393161A98">
    <summary>#rdfig calendar meeting</summary>
    <tstart
    rdf:datatype="http://www.w3.org/2002/12/cal/tzd/Europe/London#tz">
    2003-02-05T17:00:00
    </dtstart>
    <dtend
    rdf:datatype="http://www.w3.org/2002/12/cal/tzd/Europe/London#tz">
    2003-02-05T18:00:00
    </dtend>
    <description>
    Email www-rdf-calendar@w3.org with agenda suggestions.
    </description>
    </Vevent>

    As you can see the values dtstart and dtend properties have their timezones expressed as URIs. This approach has following disadvantages:

    2.5 Alignment with contact ontology

    Tight integration between ontologies has been identified as one of the core requirements for NIE (see here). ICALTZD makes no references to any specific ontology that would make it possible to link calendar events with actual contact information about attendees and organizers.

    3. NCAL Development process

    Issues outlined in the previous section led to a decision to create a new calendaring ontology for Nepomuk. The main goal was to solve the problems described above while retaining compatibility with Nepomuk guidelines.

    Development of NCAL began with the ICALTZD ontology. A Java program has been written that transformed it into RDFS and performed some basic transformations. These transformations included:

    It became clear that some properties require special classes as their ranges. They would provide explicit hooks to attach the property parameters. In order to get an overview of the needs the definitions of properties in RFC 2445 have been examined carefully. A table has been created with basic information about each property. It had following columns:

    This table quickly visualised the actual relations between properties and parameters. It enabled us to divide the ical properties into six groups. For each group an approach to represent it in RDF has been chosen.

    4. Differences between NCAL and ICALTZD

    The overall structure of NCAL is in most respects similar to ICALTZD, which is thoroughly described in [ICALNOTE]. NCAL only tries to clarify certain underspecified points, as outlined in the sections above. Following paragraphs describe two important changes that break the continuity with ICALTZD.

    4.1 Timezones

    As already mentioned, NCAL introduces the NcalDateTime class (see ncal:NcalDateTime). It's purpose is to provide a more elegant way to link the time values with their timezones. It can also represent plain dates, which models the fact that four properties have two possible value types: date and date-time. It allows for a clean link between the time value and the timezone (expressed with the ncal:ncalTimezone). Since RFC states that each icalendar document MUST contain exact definitions of all timezones used, it can safely be assumed that all time values can refer to those definitions.

    4.2 Alignment with NCO

    According to the guidelines for NIE (see sec. here), it is desirable to promote integration between ontologies. That's why ranges of two properties (namely: ncal:attendee and ncal:organizer have been equiped with links to the nco:Contact class from the Nepomuk Contact Ontology. This will facilitate integration between addressbooks and calendars.

    4.3 Union Classes

    ICALTZD used OWL unions to define domains of many properties. They don't have their equivalents in NRL, so another solution has been adopted. Each union is now represented as a separate class with whose name has been generated by concatenating the names of classes that comprise the union. (such as UnionOfEventFreebusy).

    The reader may now feel the urge to give more "meaningful" (semantic) names to the union classes. It is difficult. The semantic meaning of a union class is defined by the properties that have it as a domain, and it was not possible for us to find a name for the Union classes based on the properies, as they are too diverse.

    5. Known limitations of NCAL

    Nepomuk Calendaring Ontology doesn't capture the whole complexity of the data model defined by RFC 2445. Following limitations have been identified.

    6. Future versions

    A major revision of NCAL is expected when the RFC 2445 is obsoleted by a new document currently in preparation in the Working Group for Calendaring and Scheduling Standards Simplification (CALSIFY) within the Internet Engineering Task Force.

    7. Examples

    Example files that show how to use the expressive power of the ontology will be published here in near future.

    References

    [ICALNOTE]
    Rdf calendar - an application of the resource description framework to icalendar datal, Dan Connolly and Libby Miller, W3C Interest Group Note 29 September 2005 http://www.w3.org/TR/rdfcal/
    [HYBRIDICAL]
    Hybrid ical rdf schema, Michael Arick and Libby Miller http://www.ilrt.bris.ac.uk/discovery/2001/06/schemas/ical-full/hybrid.rdf
    [TIMBLICAL]
    A quick look at icalendar, Tim Berners-Lee http://www.w3.org/2000/01/foo
    [ANOTHERICAL]
    Another icalendar model, Dan Connoly http://www.w3.org/2000/10/swap/pim/ical.rdf
    [PALMICAL]
    Palm datebook, Dan Connoly http://www.w3.org/2000/08/palm56/datebook
    [RFC2445]
    Internet calendaring and scheduling core objects specification, Frank Dawson and Derik Stenerson http://www.ietf.org/rfc/rfc2445.txt
    [SWAD37]
    Swad-europe deliverable 3.7: Developer workshop report 2 - semantic web calendaring, Libby Miller http://www.w3.org/2001/sw/Europe/reports/dev_workshop_report_2/
    [NRLSPEC]
    Nepomuk Representational Language (NRL) Vocabulary Specification., Nepomuk Task-Force Ontologies, http://www.semanticdesktop.org/ontologies/nrl

    Ontology Classes Description

    AccessClassification

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:class
    Description Access classification of a calendar component. Introduced to express the set of values for the ncal:class property. The user may use instances provided with this ontology or create his/her own with desired semantics. See the documentation of ncal:class for details.
    Instances ncal:confidentialClassification, ncal:privateClassification, ncal:publicClassification

    Alarm

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventFreebusyTodo, ncal:UnionOfAlarmEventJournalTodo, ncal:UnionOfAlarmEventTodo, ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:action, ncal:repeat
    In range of: --
    Description Provide a grouping of component properties that define an alarm.

    AlarmAction

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:action
    Description Action to be performed on alarm. This class has been introduced to express the limited set of values of the ncal:action property. Please refer to the documentation of ncal:action for details.
    Instances ncal:audioAction, ncal:displayAction, ncal:emailAction, ncal:procedureAction

    Attachment

    Superclasses nfo:Attachment, nie:DataObject, nfo:EmbeddedFileDataObject, nfo:FileDataObject, rdfs:Resource
    Subclasses --
    In domain of: ncal:attachmentContent, ncal:attachmentUri, ncal:encoding, ncal:fmttype
    In range of: ncal:attach
    Description An object attached to a calendar entity. This class has been introduced to serve as a structured value of the ncal:attach property. See the documentation of ncal:attach for details.

    AttachmentEncoding

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:encoding
    Description Attachment encoding. This class has been introduced to express the limited vocabulary of values for the ncal:encoding property. See the documentation of ncal:encoding for details.
    Instances ncal:\_8bitEncoding, ncal:base64Encoding

    Attendee

    Superclasses ncal:AttendeeOrOrganizer, rdfs:Resource
    Subclasses --
    In domain of: ncal:cutype, ncal:delegatedFrom, ncal:delegatedTo, ncal:member, ncal:partstat, ncal:role, ncal:rsvp
    In range of: ncal:attendee
    Description An attendee of an event. This class has been introduced to serve as the range for ncal:attendee property. See documentation of ncal:attendee for details.

    AttendeeOrOrganizer

    Superclasses rdfs:Resource
    Subclasses ncal:Attendee, ncal:Organizer
    In domain of: ncal:dir, ncal:involvedContact, ncal:sentBy
    In range of: --
    Description A common superclass for ncal:Attendee and ncal:Organizer.

    AttendeeRole

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:role
    Description A role the attendee is going to play during an event. This class has been introduced to express the limited vocabulary for the values of ncal:role property. Please refer to the documentation of ncal:role for details.
    Instances ncal:chairRole, ncal:nonParticipantRole, ncal:optParticipantRole, ncal:reqParticipantRole

    BydayRulePart

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: ncal:bydayModifier, ncal:bydayWeekday
    In range of: ncal:byday
    Description Expresses the compound value of a byday part of a recurrence rule. It stores the weekday and the integer modifier. Inspired by RFC 2445 sec. 4.3.10

    Calendar

    Superclasses nie:InformationElement, rdfs:Resource
    Subclasses --
    In domain of: ncal:calscale, ncal:component, ncal:method, ncal:prodid, ncal:version
    In range of: --
    Description A calendar. Inspirations for this class can be traced to the VCALENDAR component defined in RFC 2445 sec. 4.4, but it may just as well be used to represent any kind of Calendar.

    CalendarDataObject

    Superclasses nie:DataObject, rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:component, ncal:hasAlarm
    Description A DataObject found in a calendar. It is usually interpreted as one of the calendar entity types (e.g. Event, Journal, Todo etc.)

    CalendarScale

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:calscale
    Description A calendar scale. This class has been introduced to provide the limited vocabulary for the ncal:calscale property.
    Instances ncal:gregorianCalendarScale

    CalendarUserType

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:cutype
    Description A calendar user type. This class has been introduced to express the limited vocabulary for the ncal:cutype property. See documentation of ncal:cutype for details.
    Instances ncal:groupUserType, ncal:individualUserType, ncal:resourceUserType, ncal:roomUserType, ncal:unknownUserType

    Event

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventFreebusyTodo, ncal:UnionOfAlarmEventJournalTodo, ncal:UnionOfAlarmEventTodo, ncal:UnionOfEventFreebusy, ncal:UnionOfEventFreebusyJournalTodo, ncal:UnionOfEventJournalTimezoneTodo, ncal:UnionOfEventJournalTodo, ncal:UnionOfEventTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:eventStatus, ncal:transp
    In range of: dcon:currentEvent, dcon:nearbyEvent, dcon:upcomingEvent
    Description Provide a grouping of component properties that describe an event.

    EventStatus

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:eventStatus
    Description A status of an event. This class has been introduced to express the limited set of values for the ncal:status property. The user may use the instances provided with this ontology or create his/her own. See the documentation for ncal:eventStatus for details.
    Instances ncal:cancelledEventStatus, ncal:confirmedStatus, ncal:tentativeStatus

    Freebusy

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventFreebusyTodo, ncal:UnionOfEventFreebusy, ncal:UnionOfEventFreebusyJournalTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:freebusy
    In range of: --
    Description Provide a grouping of component properties that describe either a request for free/busy time, describe a response to a request for free/busy time or describe a published set of busy time.

    FreebusyPeriod

    Superclasses ncal:NcalPeriod, ncal:NcalTimeEntity, rdfs:Resource
    Subclasses --
    In domain of: ncal:fbtype
    In range of: ncal:freebusy
    Description An aggregate of a period and a freebusy type. This class has been introduced to serve as a range of the ncal:freebusy property. See documentation for ncal:freebusy for details. Note that the specification of freebusy property states that the period is to be expressed using UTC time, so the timezone properties should NOT be used for instances of this class.

    FreebusyType

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:fbtype
    Description Type of a Freebusy indication. This class has been introduced to serve as a limited set of values for the ncal:fbtype property. See the documentation of ncal:fbtype for details.
    Instances ncal:busyFreebusyType, ncal:busyTentativeFreebusyType, ncal:busyUnavailableFreebusyType, ncal:freeFreebusyType

    Journal

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventJournalTodo, ncal:UnionOfEventFreebusyJournalTodo, ncal:UnionOfEventJournalTimezoneTodo, ncal:UnionOfEventJournalTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:journalStatus
    In range of: --
    Description Provide a grouping of component properties that describe a journal entry.

    JournalStatus

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:journalStatus
    Description A status of a journal entry. This class has been introduced to express the limited set of values for the ncal:status property. The user may use the instances provided with this ontology or create his/her own. See the documentation for ncal:journalStatus for details.
    Instances ncal:cancelledJournalStatus, ncal:draftStatus, ncal:finalStatus

    NcalDateTime

    Superclasses ncal:NcalTimeEntity, rdfs:Resource
    Subclasses --
    In domain of: ncal:date, ncal:dateTime, ncal:ncalTimezone
    In range of: ncal:dtend, ncal:dtstart, ncal:due, ncal:exdate, ncal:recurrenceIdDateTime
    Description

    NcalPeriod

    Superclasses ncal:NcalTimeEntity, rdfs:Resource
    Subclasses ncal:FreebusyPeriod
    In domain of: ncal:periodBegin, ncal:periodDuration, ncal:periodEnd
    In range of: --
    Description A period of time. Inspired by the PERIOD datatype specified in RFC 2445 sec. 4.3.9

    NcalTimeEntity

    Superclasses rdfs:Resource
    Subclasses ncal:FreebusyPeriod, ncal:NcalDateTime, ncal:NcalPeriod
    In domain of: --
    In range of: ncal:rdate
    Description A time entity. Conceived as a common superclass for NcalDateTime and NcalPeriod. According to RFC 2445 both DateTime and Period can be interpreted in different timezones. The first case is explored in many properties. The second case is theoretically possible in ncal:rdate property. Therefore the timezone properties have been defined at this level.

    Organizer

    Superclasses ncal:AttendeeOrOrganizer, rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:organizer
    Description An organizer of an event. This class has been introduced to serve as a range of ncal:organizer property. See documentation of ncal:organizer for details.

    ParticipationStatus

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:partstat
    Description Participation Status. This class has been introduced to express the limited vocabulary of values for the ncal:partstat property. See the documentation of ncal:partstat for details.
    Instances ncal:acceptedParticipationStatus, ncal:completedParticipationStatus, ncal:declinedParticipationStatus, ncal:delegatedParticipationStatus, ncal:inProcessParticipationStatus, ncal:needsActionParticipationStatus, ncal:tentativeParticipationStatus

    RecurrenceFrequency

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:freq
    Description Frequency of a recurrence rule. This class has been introduced to express a limited set of allowed values for the ncal:freq property. See the documentation of ncal:freq for details.
    Instances ncal:daily, ncal:hourly, ncal:minutely, ncal:monthly, ncal:secondly, ncal:weekly, ncal:yearly

    RecurrenceIdentifier

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: ncal:range, ncal:recurrenceIdDateTime
    In range of: ncal:recurrenceId
    Description Recurrence Identifier. Introduced to provide a structure for the value of ncal:recurrenceId property. See the documentation of ncal:recurrenceId for details.

    RecurrenceIdentifierRange

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:range
    Description Recurrence Identifier Range. This class has been created to provide means to express the limited set of values for the ncal:range property. See documentation for ncal:range for details.
    Instances ncal:thisAndFutureRange, ncal:thisAndPriorRange

    RecurrenceRule

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: ncal:byday, ncal:byhour, ncal:byminute, ncal:bymonth, ncal:bymonthday, ncal:bysecond, ncal:bysetpos, ncal:byweekno, ncal:byyearday, ncal:count, ncal:freq, ncal:interval, ncal:until, ncal:wkst
    In range of: ncal:exrule, ncal:rrule
    Description

    RequestStatus

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: ncal:requestStatusData, ncal:returnStatus, ncal:statusDescription
    In range of: ncal:requestStatus
    Description Request Status. A class that was introduced to provide a structure for the value of ncal:requestStatus property. See documentation for ncal:requestStatus for details.

    TimeTransparency

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:transp
    Description Time transparency. Introduced to provide a way to express the limited vocabulary for the values of ncal:transp property. See documentation of ncal:transp for details.
    Instances ncal:opaqueTransparency, ncal:transparentTransparency

    Timezone

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfEventJournalTimezoneTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:daylight, ncal:standard, ncal:tzid, ncal:tzurl
    In range of: ncal:ncalTimezone
    Description Provide a grouping of component properties that defines a time zone.

    TimezoneObservance

    Superclasses rdfs:Resource, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:tzname, ncal:tzoffsetfrom, ncal:tzoffsetto
    In range of: ncal:daylight, ncal:standard
    Description

    Todo

    Superclasses nie:InformationElement, rdfs:Resource, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventFreebusyTodo, ncal:UnionOfAlarmEventJournalTodo, ncal:UnionOfAlarmEventTodo, ncal:UnionOfEventFreebusyJournalTodo, ncal:UnionOfEventJournalTimezoneTodo, ncal:UnionOfEventJournalTodo, ncal:UnionOfEventTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionParentClass
    Subclasses --
    In domain of: ncal:completed, ncal:due, ncal:percentComplete, ncal:todoStatus
    In range of: dcon:currentTask, dcon:upcomingTask
    Description Provide a grouping of calendar properties that describe a to-do.

    TodoStatus

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:todoStatus
    Description A status of a calendar entity. This class has been introduced to express the limited set of values for the ncal:status property. The user may use the instances provided with this ontology or create his/her own. See the documentation for ncal:todoStatus for details.
    Instances ncal:cancelledTodoStatus, ncal:completedStatus, ncal:inProcessStatus, ncal:needsActionStatus

    Trigger

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: ncal:related, ncal:triggerDateTime, ncal:triggerDuration
    In range of: ncal:trigger
    Description An alarm trigger. This class has been created to serve as the range of ncal:trigger property. See the documentation for ncal:trigger for more details.

    TriggerRelation

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:related
    Description The relation between the trigger and its parent calendar component. This class has been introduced to express the limited vocabulary for the ncal:related property. See the documentation for ncal:related for more details.
    Instances ncal:endTriggerRelation, ncal:startTriggerRelation

    UnionOfAlarmEventFreebusyJournalTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Alarm, ncal:Event, ncal:Freebusy, ncal:Journal, ncal:Todo
    In domain of: ncal:attendee
    In range of: --
    Description

    UnionOfAlarmEventFreebusyTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Alarm, ncal:Event, ncal:Freebusy, ncal:Todo
    In domain of: ncal:duration
    In range of: --
    Description

    UnionOfAlarmEventJournalTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Alarm, ncal:Event, ncal:Journal, ncal:Todo
    In domain of: ncal:attach, ncal:description, ncal:descriptionAltRep, ncal:summary, ncal:summaryAltRep
    In range of: --
    Description

    UnionOfAlarmEventTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Alarm, ncal:Event, ncal:Todo
    In domain of: ncal:trigger
    In range of: --
    Description

    UnionOfEventFreebusy

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Freebusy
    In domain of: ncal:dtend
    In range of: --
    Description

    UnionOfEventFreebusyJournalTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Freebusy, ncal:Journal, ncal:Todo
    In domain of: ncal:contact, ncal:contactAltRep, ncal:dtstamp, ncal:organizer, ncal:requestStatus, ncal:uid, ncal:url
    In range of: --
    Description

    UnionOfEventJournalTimezoneTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Journal, ncal:Timezone, ncal:Todo
    In domain of: ncal:exdate, ncal:lastModified, ncal:recurrenceId
    In range of: --
    Description

    UnionOfEventJournalTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Journal, ncal:Todo
    In domain of: ncal:categories, ncal:class, ncal:created, ncal:exrule, ncal:ncalRelation, ncal:relatedToChild, ncal:relatedToParent, ncal:relatedToSibling, ncal:sequence
    In range of: --
    Description

    UnionOfEventTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Todo
    In domain of: ncal:geo, ncal:hasAlarm, ncal:location, ncal:locationAltRep, ncal:priority, ncal:resources, ncal:resourcesAltRep
    In range of: --
    Description

    UnionOfTimezoneObservanceEventFreebusyJournalTimezoneTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Freebusy, ncal:Journal, ncal:Timezone, ncal:TimezoneObservance, ncal:Todo
    In domain of: ncal:comment, ncal:commentAltRep
    In range of: --
    Description

    UnionOfTimezoneObservanceEventFreebusyTimezoneTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Freebusy, ncal:Timezone, ncal:TimezoneObservance, ncal:Todo
    In domain of: ncal:dtstart
    In range of: --
    Description

    UnionOfTimezoneObservanceEventJournalTimezoneTodo

    Superclasses rdfs:Resource, ncal:UnionParentClass
    Subclasses ncal:Event, ncal:Journal, ncal:Timezone, ncal:TimezoneObservance, ncal:Todo
    In domain of: ncal:rdate, ncal:rrule
    In range of: --
    Description

    UnionParentClass

    Superclasses rdfs:Resource
    Subclasses ncal:Alarm, ncal:Event, ncal:Freebusy, ncal:Journal, ncal:Timezone, ncal:TimezoneObservance, ncal:Todo, ncal:UnionOfAlarmEve..., ncal:UnionOfAlarmEventFreebusyTodo, ncal:UnionOfAlarmEventJournalTodo, ncal:UnionOfAlarmEventTodo, ncal:UnionOfEventFreebusy, ncal:UnionOfEventFreebusyJournalTodo, ncal:UnionOfEventJournalTimezoneTodo, ncal:UnionOfEventJournalTodo, ncal:UnionOfEventTodo, ncal:UnionOfTimezone..., ncal:UnionOfTimezone..., ncal:UnionOfTimezone...
    In domain of: --
    In range of: --
    Description

    Weekday

    Superclasses rdfs:Resource
    Subclasses --
    In domain of: --
    In range of: ncal:bydayWeekday, ncal:wkst
    Description Day of the week. This class has been created to provide the limited vocabulary for ncal:byday property. See the documentation for ncal:byday for details.
    Instances ncal:friday, ncal:monday, ncal:saturday, ncal:sunday, ncal:thursday, ncal:tuesday, ncal:wednesday

    Ontology Properties Description

    action

    Type rdf:Property, rdfs:Resource
    Domain ncal:Alarm
    Range ncal:AlarmAction
    Superproperties --
    Subproperties --
    Description This property defines the action to be invoked when an alarm is triggered. Inspired by RFC 2445 sec 4.8.6.1. Originally this property had a limited set of values. They are expressed as instances of the AlarmAction class.

    attach

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventJournalTodo
    Range ncal:Attachment
    Superproperties dcterms:hasPart, nie:hasPart, nie:relatedTo, dc:relation
    Subproperties --
    Description The property provides the capability to associate a document object with a calendar component. Defined in the RFC 2445 sec. 4.8.1.1

    attachmentContent

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attachment
    Range xsd:string
    Superproperties --
    Subproperties --
    Description The uri of the attachment. Created to express the actual value of the ATTACH property defined in RFC 2445 sec. 4.8.1.1. This property expresses the BINARY datatype of that property. see ncal:attachmentUri for the URI datatype.

    attachmentUri

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attachment
    Range rdfs:Resource
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The uri of the attachment. Created to express the actual value of the ATTACH property defined in RFC 2445 sec. 4.8.1.1. This property expresses the default URI datatype of that property. see ncal:attachmentContents for the BINARY datatype.

    attendee

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEve...
    Range ncal:Attendee
    Superproperties --
    Subproperties --
    Description The property defines an "Attendee" within a calendar component. Inspired by RFC 2445 sec. 4.8.4.1. Originally this property accepted many parameters. The Attendee class has been introduced to express them all. Note that NCAL is aligned with NCO. The actual value (of the CAL-ADDRESS type) is expressed as an instance of nco:Contact. Remember that the CN parameter has been removed from NCAL. Instead that value should be expressed using nco:fullname property of the above mentioned nco:Contact instance. The RFC stated that whenever this property is attached to a Valarm instance, the Attendee cannot have any parameters apart from involvedContact.

    byday

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range ncal:BydayRulePart
    Superproperties --
    Subproperties --
    Description Weekdays the recurrence should occur. Defined in RFC 2445 sec. 4.3.10

    bydayModifier

    Type rdf:Property, rdfs:Resource
    Domain ncal:BydayRulePart
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description An integer modifier for the BYDAY rule part. Each BYDAY value can also be preceded by a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific day within the MONTHLY or YEARLY RRULE. For example, within a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday within the month, whereas -1MO represents the last Monday of the month. If an integer modifier is not present, it means all days of this type within the specified frequency. For example, within a MONTHLY rule, MO represents all Mondays within the month. Inspired by RFC 2445 sec. 4.3.10

    bydayWeekday

    Type rdf:Property, rdfs:Resource
    Domain ncal:BydayRulePart
    Range ncal:Weekday
    Superproperties --
    Subproperties --
    Description Connects a BydayRulePath with a weekday.

    byhour

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Hour of recurrence. Defined in RFC 2445 sec. 4.3.10

    byminute

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Minute of recurrence. Defined in RFC 2445 sec. 4.3.10

    bymonth

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Number of the month of the recurrence. Valid values are integers from 1 (January) to 12 (December). Defined in RFC 2445 sec. 4.3.10

    bymonthday

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Day of the month when the event should recur. Defined in RFC 2445 sec. 4.3.10

    bysecond

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Second of a recurrence. Defined in RFC 2445 sec. 4.3.10

    bysetpos

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description The BYSETPOS rule part specify values which correspond to the nth occurrence within the set of events specified by the rule. Valid values are 1 to 366 or -366 to -1. It MUST only be used in conjunction with another BYxxx rule part. For example "the last work day of the month" could be represented as: RRULE: FREQ=MONTHLY; BYDAY=MO, TU, WE, TH, FR; BYSETPOS=-1. Each BYSETPOS value can include a positive (+n) or negative (-n) integer. If present, this indicates the nth occurrence of the specific occurrence within the set of events specified by the rule. Defined in RFC 2445 sec. 4.3.10

    byweekno

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description The number of the week an event should recur. Defined in RFC 2445 sec. 4.3.10

    byyearday

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description Day of the year the event should occur. Defined in RFC 2445 sec. 4.3.10

    calscale

    Type rdf:Property, rdfs:Resource
    Domain ncal:Calendar
    Range ncal:CalendarScale
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the calendar scale used for the calendar information specified in the iCalendar object. Defined in RFC 2445 sec. 4.7.1

    categories

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:string
    Superproperties --
    Subproperties --
    Description Categories for a calendar component. Inspired by RFC 2445 sec 4.8.1.2 with the following reservations: The LANGUAGE parameter has been discarded. Please use xml:lang literals to express multiple languages. This property can specify multiple comma-separated categories. The order of categories doesn't matter. Please use a separate triple for each category.

    class

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range ncal:AccessClassification
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines the access classification for a calendar component. Inspired by RFC 2445 sec. 4.8.1.3 with the following reservations: this property has limited vocabulary. Possible values are: PUBLIC, PRIVATE and CONFIDENTIAL. The default is PUBLIC. Those values are expressed as instances of the AccessClassification class. The user may create his/her own if necessary.

    comment

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfTimezone...
    Range xsd:string
    Superproperties nie:comment
    Subproperties --
    Description Non-processing information intended to provide a comment to the calendar user. Inspired by RFC 2445 sec. 4.8.1.4 with the following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the commentAltRep property.

    commentAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfTimezone...
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the comment. Introduced to cover the ALTREP parameter of the COMMENT property. See documentation of ncal:comment for details.

    completed

    Type rdf:Property, rdfs:Resource
    Domain ncal:Todo
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the date and time that a to-do was actually completed. Inspired by RFC 2445 sec. 4.8.2.1. Note that the RFC allows ONLY UTC time values for this property.

    component

    Type rdf:Property, rdfs:Resource
    Domain ncal:Calendar
    Range ncal:CalendarDataObject
    Superproperties dcterms:hasPart, nie:hasPart, nie:relatedTo, dc:relation
    Subproperties --
    Description Links the Vcalendar instance with the calendar components. This property has no direct equivalent in the RFC specification. It has been introduced to express the containmnent relations.

    contact

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range xsd:string
    Superproperties --
    Subproperties --
    Description The property is used to represent contact information or alternately a reference to contact information associated with the calendar component. Inspired by RFC 2445 sec. 4.8.4.2 with the following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the contactAltRep property.RFC doesn't define any format for the string.

    contactAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the contact property. Introduced to cover the ALTREP parameter of the CONTACT property. See documentation of ncal:contact for details.

    count

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description How many times should an event be repeated. Defined in RFC 2445 sec. 4.3.10

    created

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties nao:annotation, dcterms:created, nie:created, nao:created, nao:modified, dcterms:modified, nie:modified
    Subproperties --
    Description This property specifies the date and time that the calendar information was created by the calendar user agent in the calendar store. Note: This is analogous to the creation date and time for a file in the file system. Inspired by RFC 2445 sec. 4.8.7.1. Note that this property is a subproperty of nie:created. The domain of nie:created is nie:DataObject. It is not a superclass of UnionOf\_Vevent\_Vjournal\_Vtodo, but since that union is conceived as an 'abstract' class, and in real-life all resources referenced by this property will also be DataObjects, than this shouldn't cause too much of a problem. Note that RFC allows ONLY UTC time values for this property.

    cutype

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range ncal:CalendarUserType
    Superproperties --
    Subproperties --
    Description To specify the type of calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.3. This parameter has a limited vocabulary. The terms that may serve as values for this property have been expressed as instances of CalendarUserType class. The user may use instances provided with this ontology or create his own.

    date

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalDateTime
    Range xsd:date
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Date an instance of NcalDateTime refers to. It was conceived to express values in DATE datatype specified in RFC 2445 4.3.4

    dateTime

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalDateTime
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Representation of a date an instance of NcalDateTime actually refers to. It's purpose is to express values in DATE-TIME datatype, as defined in RFC 2445 sec. 4.3.5

    daylight

    Type rdf:Property, rdfs:Resource
    Domain ncal:Timezone
    Range ncal:TimezoneObservance
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Links a timezone with it's daylight observance. This property has no direct equivalent in the RFC 2445. It has been inspired by the structure of the Vtimezone component defined in sec.4.6.5

    delegatedFrom

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range nco:Contact
    Superproperties --
    Subproperties --
    Description To specify the calendar users that have delegated their participation to the calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.4. Originally the value type for this property was CAL-ADDRESS. This has been expressed as nco:Contact to promote integration between NCAL and NCO.

    delegatedTo

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range nco:Contact
    Superproperties --
    Subproperties --
    Description To specify the calendar users to whom the calendar user specified by the property has delegated participation. Inspired by RFC 2445 sec. 4.2.5. Originally the value type for this parameter was CAL-ADDRESS. This has been expressed as nco:Contact to promote integration between NCAL and NCO.

    description

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventJournalTodo
    Range xsd:string
    Superproperties nao:annotation, rdfs:comment, nie:description, nao:description, dc:description
    Subproperties --
    Description A more complete description of the calendar component, than that provided by the ncal:summary property.Inspired by RFC 2445 sec. 4.8.1.5 with following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the descriptionAltRep property.

    descriptionAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventJournalTodo
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the calendar entity description. Introduced to cover the ALTREP parameter of the DESCRIPTION property. See documentation of ncal:description for details.

    dir

    Type rdf:Property, rdfs:Resource
    Domain ncal:AttendeeOrOrganizer
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Specifies a reference to a directory entry associated with the calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.6. Originally the data type of the value of this parameter was URI (Usually an LDAP URI). This has been expressed as rdfs:resource.

    dtend

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusy
    Range ncal:NcalDateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies the date and time that a calendar component ends. Inspired by RFC 2445 sec. 4.8.2.2

    dtstamp

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The property indicates the date/time that the instance of the iCalendar object was created. Inspired by RFC 2445 sec. 4.8.7.1. Note that the RFC allows ONLY UTC values for this property.

    dtstart

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfTimezone...
    Range ncal:NcalDateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies when the calendar component begins. Inspired by RFC 2445 sec. 4.8.2.4

    due

    Type rdf:Property, rdfs:Resource
    Domain ncal:Todo
    Range ncal:NcalDateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the date and time that a to-do is expected to be completed. Inspired by RFC 2445 sec. 4.8.2.3

    duration

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventFreebusyTodo
    Range xsd:duration
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The property specifies a positive duration of time. Inspired by RFC 2445 sec. 4.8.2.5

    encoding

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attachment
    Range ncal:AttachmentEncoding
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description To specify an alternate inline encoding for the property value. Inspired by RFC 2445 sec. 4.2.7. Originally this property had a limited vocabulary. ('8BIT' and 'BASE64'). The terms of this vocabulary have been expressed as instances of the AttachmentEncoding class

    eventStatus

    Type rdf:Property, rdfs:Resource
    Domain ncal:Event
    Range ncal:EventStatus
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines the overall status or confirmation for an Event. Based on the STATUS property defined in RFC 2445 sec. 4.8.1.11.

    exdate

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTimezoneTodo
    Range ncal:NcalDateTime
    Superproperties --
    Subproperties --
    Description This property defines the list of date/time exceptions for a recurring calendar component. Inspired by RFC 2445 sec. 4.8.5.1

    exrule

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range ncal:RecurrenceRule
    Superproperties --
    Subproperties --
    Description This property defines a rule or repeating pattern for an exception to a recurrence set. Inspired by RFC 2445 sec. 4.8.5.2.

    fbtype

    Type rdf:Property, rdfs:Resource
    Domain ncal:FreebusyPeriod
    Range ncal:FreebusyType
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description To specify the free or busy time type. Inspired by RFC 2445 sec. 4.2.9. The RFC specified a limited vocabulary for the values of this property. The terms of this vocabulary have been expressed as instances of the FreebusyType class. The user can use instances provided with this ontology or create his own.

    fmttype

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attachment
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description To specify the content type of a referenced object. Inspired by RFC 2445 sec. 4.2.8. The value of this property should be an IANA-registered content type (e.g. application/binary)

    freebusy

    Type rdf:Property, rdfs:Resource
    Domain ncal:Freebusy
    Range ncal:FreebusyPeriod
    Superproperties --
    Subproperties --
    Description The property defines one or more free or busy time intervals. Inspired by RFC 2445 sec. 4.8.2.6. Note that the periods specified by this property can only be expressed with UTC times. Originally this property could have many comma-separated values. Please use a separate triple for each value.

    freq

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range ncal:RecurrenceFrequency
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Frequency of a recurrence rule. Defined in RFC 2445 sec. 4.3.10

    geo

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range geo:Point
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies information related to the global position for the activity specified by a calendar component. Inspired by RFC 2445 sec. 4.8.1.6

    hasAlarm

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range ncal:CalendarDataObject
    Superproperties dcterms:hasPart, nie:hasPart, nie:relatedTo, dc:relation
    Subproperties --
    Description Links an event or a todo with a DataObject that can be interpreted as an alarm. This property has no direct equivalent in the RFC 2445. It has been provided to express this relation.

    interval

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The INTERVAL rule part contains a positive integer representing how often the recurrence rule repeats. The default value is "1", meaning every second for a SECONDLY rule, or every minute for a MINUTELY rule, every hour for an HOURLY rule, every day for a DAILY rule, every week for a WEEKLY rule, every month for a MONTHLY rule andevery year for a YEARLY rule. Defined in RFC 2445 sec. 4.3.10

    involvedContact

    Type rdf:Property, rdfs:Resource
    Domain ncal:AttendeeOrOrganizer
    Range nco:Contact
    Superproperties --
    Subproperties --
    Description A contact of the Attendee or the organizer involved in an event or other calendar entity. This property has been introduced to express the actual value of the ATTENDEE and ORGANIZER properties. The contact will also represent the CN parameter of those properties. See documentation of ncal:attendee or ncal:organizer for more details.

    journalStatus

    Type rdf:Property, rdfs:Resource
    Domain ncal:Journal
    Range ncal:JournalStatus
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines the overall status or confirmation for a journal entry. Based on the STATUS property defined in RFC 2445 sec. 4.8.1.11.

    lastModified

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTimezoneTodo
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The property specifies the date and time that the information associated with the calendar component was last revised in the calendar store. Note: This is analogous to the modification date and time for a file in the file system. Inspired by RFC 2445 sec. 4.8.7.3. Note that the RFC allows ONLY UTC time values for this property.

    location

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines the intended venue for the activity defined by a calendar component. Inspired by RFC 2445 sec 4.8.1.7 with the following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the locationAltRep property.

    locationAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the event or todo location. Introduced to cover the ALTREP parameter of the LOCATION property. See documentation of ncal:location for details.

    member

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range nco:Contact
    Superproperties --
    Subproperties --
    Description To specify the group or list membership of the calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.11. Originally this parameter had a value type of CAL-ADDRESS. This has been expressed as nco:Contact to promote integration between NCAL and NCO

    method

    Type rdf:Property, rdfs:Resource
    Domain ncal:Calendar
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the iCalendar object method associated with the calendar object. Defined in RFC 2445 sec. 4.7.2

    ncalRelation

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:string
    Superproperties dc:relation
    Subproperties ncal:relatedToChild, ncal:relatedToParent, ncal:relatedToSibling
    Description A common superproperty for all types of ncal relations. It is not to be used directly.

    ncalTimezone

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalDateTime
    Range ncal:Timezone
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The timezone instance that should be used to interpret an NcalDateTime. The purpose of this property is similar to the TZID parameter specified in RFC 2445 sec. 4.2.19

    organizer

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range ncal:Organizer
    Superproperties --
    Subproperties --
    Description The property defines the organizer for a calendar component. Inspired by RFC 2445 sec. 4.8.4.3. Originally this property accepted many parameters. The Organizer class has been introduced to express them all. Note that NCAL is aligned with NCO. The actual value (of the CAL-ADDRESS type) is expressed as an instance of nco:Contact. Remember that the CN parameter has been removed from NCAL. Instead that value should be expressed using nco:fullname property of the above mentioned nco:Contact instance.

    partstat

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range ncal:ParticipationStatus
    Superproperties --
    Subproperties --
    Description To specify the participation status for the calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.12. Originally this parameter had three sets of allowed values. Which set applied to a particular case - depended on the type of calendar entity this parameter occured in. (event, todo, journal entry). This would be awkward to model in RDF so a single ParticipationStatus class has been introduced. Terms of the values vocabulary are expressed as instances of this class. Users are advised to pay attention which instances they use.

    percentComplete

    Type rdf:Property, rdfs:Resource
    Domain ncal:Todo
    Range xsd:integer
    Superproperties --
    Subproperties --
    Description This property is used by an assignee or delegatee of a to-do to convey the percent completion of a to-do to the Organizer. Inspired by RFC 2445 sec. 4.8.1.8

    periodBegin

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalPeriod
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Beginng of a period. Inspired by the first part of a structured value of the PERIOD datatype specified in RFC 2445 sec. 4.3.9

    periodDuration

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalPeriod
    Range xsd:duration
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Duration of a period of time. Inspired by the second part of a structured value of the PERIOD datatype specified in RFC 2445 sec. 4.3.9. Note that a single NcalPeriod instance shouldn't have the periodEnd and periodDuration properties specified simultaneously.

    periodEnd

    Type rdf:Property, rdfs:Resource
    Domain ncal:NcalPeriod
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description End of a period of time. Inspired by the second part of a structured value of a PERIOD datatype specified in RFC 2445 sec. 4.3.9. Note that a single NcalPeriod instance shouldn't have the periodEnd and periodDuration properties specified simultaneously.

    priority

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The property defines the relative priority for a calendar component. Inspired by RFC 2445 sec. 4.8.1.9

    prodid

    Type rdf:Property, rdfs:Resource
    Domain ncal:Calendar
    Range xsd:string
    Superproperties nie:generator
    Subproperties --
    Description This property specifies the identifier for the product that created the iCalendar object. Defined in RFC 2445 sec. 4.7.2

    range

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceIdentifier
    Range ncal:RecurrenceIdentifierRange
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description To specify the effective range of recurrence instances from the instance specified by the recurrence identifier specified by the property. It is intended to express the RANGE parameter specified in RFC 2445 sec. 4.2.13. The set of possible values for this property is limited. See also the documentation for ncal:recurrenceId for more details.

    rdate

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfTimezone...
    Range ncal:NcalTimeEntity
    Superproperties --
    Subproperties --
    Description This property defines the list of date/times for a recurrence set. Inspired by RFC 2445 sec. 4.8.5.3. Note that RFC allows both DATE, DATE-TIME and PERIOD values for this property. That's why the range has been set to NcalTimeEntity.

    recurrenceId

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTimezoneTodo
    Range ncal:RecurrenceIdentifier
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property is used in conjunction with the "UID" and "SEQUENCE" property to identify a specific instance of a recurring "VEVENT", "VTODO" or "VJOURNAL" calendar component. The property value is the effective value of the "DTSTART" property of the recurrence instance. Inspired by the RFC 2445 sec. 4.8.4.4

    recurrenceIdDateTime

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceIdentifier
    Range ncal:NcalDateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The date and time of a recurrence identifier. Provided to express the actual value of the ncal:recurrenceId property. See documentation for ncal:recurrenceId for details.

    related

    Type rdf:Property, rdfs:Resource
    Domain ncal:Trigger
    Range ncal:TriggerRelation
    Superproperties --
    Subproperties --
    Description To specify the relationship of the alarm trigger with respect to the start or end of the calendar component. Inspired by RFC 2445 4.2.14. The RFC has specified two possible values for this property ('START' and 'END') they have been expressed as instances of the TriggerRelation class.

    relatedToChild

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:string
    Superproperties ncal:ncalRelation, dc:relation
    Subproperties --
    Description The property is used to represent a relationship or reference between one calendar component and another. Inspired by RFC 2445 sec. 4.8.4.5. Originally this property had a RELTYPE parameter. It has been decided to introduce three different properties to express the values of that parameter. This property expresses the RELATED-TO property with RELTYPE=CHILD parameter.

    relatedToParent

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:string
    Superproperties ncal:ncalRelation, dc:relation
    Subproperties --
    Description The property is used to represent a relationship or reference between one calendar component and another. Inspired by RFC 2445 sec. 4.8.4.5. Originally this property had a RELTYPE parameter. It has been decided that it is more natural to introduce three different properties to express the values of that parameter. This property expresses the RELATED-TO property with no RELTYPE parameter (the default value is PARENT), or with explicit RELTYPE=PARENT parameter.

    relatedToSibling

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:string
    Superproperties ncal:ncalRelation, dc:relation
    Subproperties --
    Description The property is used to represent a relationship or reference between one calendar component and another. Inspired by RFC 2445 sec. 4.8.4.5. Originally this property had a RELTYPE parameter. It has been decided that it is more natural to introduce three different properties to express the values of that parameter. This property expresses the RELATED-TO property with RELTYPE=SIBLING parameter.

    repeat

    Type rdf:Property, rdfs:Resource
    Domain ncal:Alarm
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the number of time the alarm should be repeated, after the initial trigger. Inspired by RFC 2445 sec. 4.8.6.2

    requestStatus

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range ncal:RequestStatus
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the status code returned for a scheduling request. Inspired by RFC 2445 sec. 4.8.8.2. Original value of this property was a four-element structure. The RequestStatus class has been introduced to express it. In RFC 2445 this property could have the LANGUAGE parameter. This has been discarded in this ontology. Use xml:lang literals to express it if necessary.

    requestStatusData

    Type rdf:Property, rdfs:Resource
    Domain ncal:RequestStatus
    Range xsd:string
    Superproperties --
    Subproperties --
    Description Additional data associated with a request status. Inspired by the third part of the structured value for the REQUEST-STATUS property defined in RFC 2445 sec. 4.8.8.2 ("Textual exception data. For example, the offending property name and value or complete property line")

    resources

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range xsd:string
    Superproperties --
    Subproperties --
    Description Defines the equipment or resources anticipated for an activity specified by a calendar entity. Inspired by RFC 2445 sec. 4.8.1.10 with the following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the resourcesAltRep property. This property specifies multiple resources. The order is not important. it is recommended to introduce a separate triple for each resource.

    resourcesAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventTodo
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the resources needed for an event or todo. Introduced to cover the ALTREP parameter of the resources property. See documentation for ncal:resources for details.

    returnStatus

    Type rdf:Property, rdfs:Resource
    Domain ncal:RequestStatus
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Short return status. Inspired by the first element of the structured value of the REQUEST-STATUS property described in RFC 2445 sec. 4.8.8.2. The short return status is a PERIOD character (US-ASCII decimal 46) separated 3-tuple of integers. For example, "3.1.1". The successive levels of integers provide for a successive level of status code granularity. The following are initial classes for the return status code. Individual iCalendar object methods will define specific return status codes for these classes. In addition, other classes for the return status code may be defined using the registration process defined later in this memo. 1.xx - Preliminary success. This class of status of status code indicates that the request has request has been initially processed but that completion is pending. 2.xx -Successful. This class of status code indicates that the request was completed successfuly. However, the exact status code can indicate that a fallback has been taken. 3.xx - Client Error. This class of status code indicates that the request was not successful. The error is the result of either a syntax or a semantic error in the client formatted request. Request should not be retried until the condition in the request is corrected. 4.xx - Scheduling Error. This class of status code indicates that the request was not successful. Some sort of error occurred within the calendaring and scheduling service, not directly related to the request itself.

    role

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range ncal:AttendeeRole
    Superproperties --
    Subproperties --
    Description To specify the participation role for the calendar user specified by the property. Inspired by the RFC 2445 sec. 4.2.16. Originally this property had a limited vocabulary for values. The terms of that vocabulary have been expressed as instances of the AttendeeRole class.

    rrule

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfTimezone...
    Range ncal:RecurrenceRule
    Superproperties --
    Subproperties --
    Description This property defines a rule or repeating pattern for recurring events, to-dos, or time zone definitions. sec. 4.8.5.4

    rsvp

    Type rdf:Property, rdfs:Resource
    Domain ncal:Attendee
    Range xsd:boolean
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description To specify whether there is an expectation of a favor of a reply from the calendar user specified by the property value. Inspired by RFC 2445 sec. 4.2.17

    sentBy

    Type rdf:Property, rdfs:Resource
    Domain ncal:AttendeeOrOrganizer
    Range nco:Contact
    Superproperties --
    Subproperties --
    Description To specify the calendar user that is acting on behalf of the calendar user specified by the property. Inspired by RFC 2445 sec. 4.2.18. The original data type of this property was a mailto: URI. This has been changed to nco:Contact to promote integration between NCO and NCAL.

    sequence

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventJournalTodo
    Range xsd:integer
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines the revision sequence number of the calendar component within a sequence of revisions. Inspired by RFC 2445 sec. 4.8.7.4

    standard

    Type rdf:Property, rdfs:Resource
    Domain ncal:Timezone
    Range ncal:TimezoneObservance
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Links the timezone with the standard timezone observance. This property has no direct equivalent in the RFC 2445. It has been inspired by the structure of the Vtimezone component defined in sec.4.6.5

    statusDescription

    Type rdf:Property, rdfs:Resource
    Domain ncal:RequestStatus
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Longer return status description. Inspired by the second part of the structured value of the REQUEST-STATUS property defined in RFC 2445 sec. 4.8.8.2

    summary

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventJournalTodo
    Range xsd:string
    Superproperties --
    Subproperties --
    Description Defines a short summary or subject for the calendar component. Inspired by RFC 2445 sec 4.8.1.12 with the following reservations: the LANGUAGE parameter has been discarded. Please use xml:lang literals to express language. For the ALTREP parameter use the summaryAltRep property.

    summaryAltRep

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventJournalTodo
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description Alternate representation of the comment. Introduced to cover the ALTREP parameter of the SUMMARY property. See documentation of ncal:summary for details.

    todoStatus

    Type rdf:Property, rdfs:Resource
    Domain ncal:Todo
    Range ncal:TodoStatus
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines the overall status or confirmation for a todo. Based on the STATUS property defined in RFC 2445 sec. 4.8.1.11.

    transp

    Type rdf:Property, rdfs:Resource
    Domain ncal:Event
    Range ncal:TimeTransparency
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description Defines whether an event is transparent or not to busy time searches. Inspired by RFC 2445 sec.4.8.2.7. Values for this property can be chosen from a limited vocabulary. To express this a TimeTransparency class has been introduced.

    trigger

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfAlarmEventTodo
    Range ncal:Trigger
    Superproperties --
    Subproperties --
    Description This property specifies when an alarm will trigger. Inspired by RFC 2445 sec. 4.8.6.3 Originally the value of this property could accept two types : duration and date-time. To express this fact a Trigger class has been introduced. It also has a related property to account for the RELATED parameter.

    triggerDateTime

    Type rdf:Property, rdfs:Resource
    Domain ncal:Trigger
    Range xsd:dateTime
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The exact date and time of the trigger. This property has been created to express the VALUE=DATE, and VALUE=DATE-TIME parameters of the TRIGGER property. See the documentation for ncal:trigger for more details

    triggerDuration

    Type rdf:Property, rdfs:Resource
    Domain ncal:Trigger
    Range xsd:duration
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The duration of a trigger. This property has been created to express the VALUE=DURATION parameter of the TRIGGER property. See documentation for ncal:trigger for more details.

    tzid

    Type rdf:Property, rdfs:Resource
    Domain ncal:Timezone
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies the text value that uniquely identifies the "VTIMEZONE" calendar component. Inspired by RFC 2445 sec 4.8.3.1

    tzname

    Type rdf:Property, rdfs:Resource
    Domain ncal:TimezoneObservance
    Range xsd:string
    Superproperties --
    Subproperties --
    Description Specifies the customary designation for a timezone description. Inspired by RFC 2445 sec. 4.8.3.2 The LANGUAGE parameter has been discarded. Please xml:lang literals to express languages. Original specification for the domain of this property stated that it must appear within the timezone component. In this ontology the TimezoneObservance class has been itroduced to clarify this specification.

    tzoffsetfrom

    Type rdf:Property, rdfs:Resource
    Domain ncal:TimezoneObservance
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies the offset which is in use prior to this time zone observance. Inspired by RFC 2445 sec. 4.8.3.3. The original domain was underspecified. It said that this property must appear within a Timezone component. In this ontology a TimezoneObservance class has been introduced to clarify this specification. The original range was UTC-OFFSET. There is no equivalent among the XSD datatypes so plain string was chosen.

    tzoffsetto

    Type rdf:Property, rdfs:Resource
    Domain ncal:TimezoneObservance
    Range xsd:string
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property specifies the offset which is in use in this time zone observance. nspired by RFC 2445 sec. 4.8.3.4. The original domain was underspecified. It said that this property must appear within a Timezone component. In this ontology a TimezoneObservance class has been introduced to clarify this specification. The original range was UTC-OFFSET. There is no equivalent among the XSD datatypes so plain string was chosen.

    tzurl

    Type rdf:Property, rdfs:Resource
    Domain ncal:Timezone
    Range rdfs:Resource
    Superproperties --
    Subproperties --
    Description The TZURL provides a means for a VTIMEZONE component to point to a network location that can be used to retrieve an up-to- date version of itself. Inspired by RFC 2445 sec. 4.8.3.5. Originally the range of this property had been specified as URI.

    uid

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range xsd:string
    Maximal cardinality 1
    Superproperties nie:identifier, dc:identifier, nao:identifier
    Subproperties --
    Description This property defines the persistent, globally unique identifier for the calendar component. Inspired by the RFC 2445 sec 4.8.4.7

    until

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range xsd:dateTime
    Superproperties --
    Subproperties --
    Description The UNTIL rule part defines a date-time value which bounds the recurrence rule in an inclusive manner. If the value specified by UNTIL is synchronized with the specified recurrence, this date or date-time becomes the last instance of the recurrence. If specified as a date-time value, then it MUST be specified in an UTC time format. If not present, and the COUNT rule part is also not present, the RRULE is considered to repeat forever.

    url

    Type rdf:Property, rdfs:Resource
    Domain ncal:UnionOfEventFreebusyJournalTodo
    Range rdfs:Resource
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description This property defines a Uniform Resource Locator (URL) associated with the iCalendar object. Inspired by the RFC 2445 sec. 4.8.4.6. Original range had been specified as URI.

    version

    Type rdf:Property, rdfs:Resource
    Domain ncal:Calendar
    Range xsd:string
    Superproperties nie:generatorOption
    Subproperties --
    Description This property specifies the identifier corresponding to the highest version number or the minimum and maximum range of the iCalendar specification that is required in order to interpret the iCalendar object. Defined in RFC 2445 sec. 4.7.4

    wkst

    Type rdf:Property, rdfs:Resource
    Domain ncal:RecurrenceRule
    Range ncal:Weekday
    Maximal cardinality 1
    Superproperties --
    Subproperties --
    Description The day that's counted as the start of the week. It is used to disambiguate the byweekno rule. Defined in RFC 2445 sec. 4.3.10