Foreword
This page provides links, titles, and very brief abstracts of Calendaring and Calendaring-related (e.g. WebDAV, vCard) standards, specifications, and guides. The material is divided by category and subdivided in turn to base standards, additions and extensions, and work in progress. Entries are alphabetical by title within section. The material linked is largely but not entirely IETF and CalConnect.
We would appreciate additions and corrections to the list; please send any recommendations to Standards Recommendations to CalConnect.
Index to Calendaring and Scheduling Standards
1. General
1.1. An Introduction to Internet Calendaring
This CalConnect guide introduces internet calendaring and the major standards and specifications related to calendaring and scheduling.
1.2. Calendaring and Scheduling Glossary of Terms
A Glossary of Calendaring and Scheduling Terms, developed by CalConnect.
2. iCalendar
2.1. Base Standards
2.1.1. Internet Calendaring and Scheduling Core Object Specification (iCalendar) RFC 5545
iCalendar is the core data schema for calendaring information. This is the new version and obsoletes RFC 2445.
2.1.2. iCalendar Transport-Independent Interoperability Protocol (iTIP) — Scheduling Events, BusyTime, To-dos and Journal Entries RFC 5546
Specifies the mechanisms for calendaring event interchange between calendar servers. This is the new version and obsoletes RFC 2446.
2.1.3. iCalendar Message-Based Interoperability Protocol (iMIP) RFC 6047
Specifies how to exchange calendaring data via e-mail. This is the new version and obsoletes RFC 2447.
2.1.4. xCal: The XML format for iCalendar RFC 6321
This specification defines a format for representing iCalendar data in XML. More specifically, is to define an XML format that allows iCalendar data to be converted to XML, and then back to iCalendar, without losing any semantic meaning in the data. Anyone creating XML calendar data according to this specification will know that their data can be converted to a valid iCalendar representation as well.
2.2. Additional and Extensions
2.2.1. CalWS RESTful Web Services Protocol for Calendaring
This document, developed by the XML Technical Committee, specifies a RESTful web services Protocol for calendaring operations. This protocol has been contributed to OASIS WS-CALENDAR as a component of the WS-CALENDAR Specification under development by OASIS.
2.2.2. Freebusy Read URL
This proposal, developed by the Freebusy Technical Committee, defines a standardized form of Freebusy Read URL to improve interoperability between client and server implementations, while extending functionality and utility through the use of optional parameters.
2.2.3. hCalendar 1.0 microformat
hCalendar is a simple, open, distributed calendaring and events format, using a 1:1 representation of standard iCalendar (RFC 2445) VEVENT properties and values in semantic HTML or XHTML.
2.2.4. IANA Registration of Enumservices for Internet Calendaring RFC 5333
This document registers Enumservices for Internet calendaring. Specifically, this document focuses on Enumservices for scheduling with iMIP (iCalendar Message-Based Interoperability Protocol) and for accessing Internet calendaring information with CalDAV (Calendaring Extensions to WebDAV).
2.3. Work in Progress
2.3.1. Calendar Availability
This document specifies a new iCalendar calendar component VAVAILABILITY that allows the publication of available and unavailable time periods associated with a calendar user. This component can be used in standard iCalendar free-busy lookups, including iTIP free-busy requests, to generate repeating blocks of available or busy time with exceptions as needed.
2.3.2. Event Publication Extensions to iCalendar
This specification introduces a number of new iCalendar properties which are of particular use for event publishers and in social networking.
2.3.3. Internet Calendar Scheduling Protocol (iSchedule)
This document defines the Internet Calendar Scheduling Protocol (iSchedule), which is a binding from the iCalendar Transport- independent Interoperability Protocol (iTIP) to the Hypertext Transfer Protocol (HTTP) to enable interoperability between calendaring and scheduling systems over the Internet.
2.3.4. LINK Property Extension to iCalendar
This specification introduces a new iCalendar property LINK to provide ancillary information for iCalendar components.
2.3.5. Masking existing meetings in iCalendar free busy requests
This document defines an extension to the iTIP calendar scheduling protocol to allow an organizer to have a specific event that may exist on an attendee’s calendar ignored when the attendee calculates and returns their free-busy information after a request from the organizer.
2.3.6. New Properties for iCalendar
This document defines a set of new properties for iCalendar data.
2.3.7. Schema for representing resources for calendaring and scheduling services
This specification describes a schema for representing resources for calendaring and scheduling. A resource in the scheduling context is any shared entity that can be scheduled by a calendar user, but does not control its own attendance status.
2.3.8. VALARM Extensions for iCalendar
This document defines a set of extensions to the iCalendar VALARM component to enhance use of alarms and improve interoperability between clients and servers.
3. CalDAV
3.1. Base Standards
3.1.1. Calendaring Extensions to WebDAV (CalDAV) RFC 4791
This document defines extensions to the Web Distributed Authoring and Versioning (WebDAV) protocol to specify a standard way of accessing, managing, and sharing calendaring and scheduling information based on the iCalendar format. This document defines the “calendar-access” feature of CalDAV.
3.3. Work in Progress
3.3.1. Calendar Collection Entity Tag (CTag) in CalDAV
This specification defines an extension to CalDAV that provides a fast way for a client to determine whether the contents of a calendar collection may have changed.
3.3.2. Calendar Usery Proxy Functionality in CalDAV
This specification defines an extension to CalDAV that makes it easy for clients to setup and manage calendar user proxies, using the WebDAV Access Control List extension as a basis.
3.3.3. Locating CalDAV and CardDAV Services
This specification describes how DNS SRV records, DNS TXT records and well-known URIs can be used together or separately to locate Calendaring Extensions to WebDAV (CalDAV) or vCard Extensions to WebDAV (CardDAV) services.
3.3.4. Scheduling Extensions to CalDAV
This document defines extensions to the Web Distributed Authoring and Versioning (WebDAV) protocol to specify a standard way of exchanging and processing scheduling messages based on the iCalendar Transport-Independent Interoperability Protocol (iTIP). This document defines the “calendar-schedule” feature of CalDAV.
Also see CalConnect CC/R 1104:2011.
4. vCard
4.1. Base Standards
4.1.1. vCard Format Specification RFC 6350
This document defines the vCard data format for representing and exchanging a variety of information about individuals and other entities (e.g., formatted and structured name and delivery addresses, email address, multiple telephone numbers, photograph, logo, audio clips, etc.). This is the new version and obsoletes RFCs 2425, 2426, and 4770, and updates RFC 2739.
4.1.2. xCard: vCard XML Representation RFC 6351
This document defines the XML schema of the vCard data format.
4.2. Additional and Extensions
4.2.1. Calendar Attributes for vCard and LDAP RFC 2739
This memo defines three mechanisms for obtaining a URI to a user’s calendar and free/busy time. These include manual transfer of the information, personal data exchange using the vCard format, and directory lookup using the LDAP protocol.
4.2.2. hCard 1.0 microformat
hCard is a simple, open, distributed format for representing people, companies, organizations, and places, using a 1:1 representation of vCard (RFC2426) properties and values in semantic HTML or XHTML.
4.3. Work in Progress
4.3.1. vCard Service Type Parameter
This document defines a “Service Type” parameter for use on various vCard properties to help clients distinguish between different types of communication services that may be using the same protocol, yet are distinct.
5. CardDAV
5.1. Base Standards
5.1.1. CardDAV: vCard Extensions to Web Distributed Authoring and Versioning (WebDAV) RFC 6352
This document defines extensions to the Web Distributed Authoring and Versioning (WebDAV) protocol to specify a standard way of accessing, managing, and sharing contact information based on the vCard format.
5.3. Work in Progress
5.3.1. CardDAV Directory Gateway Extension
This document defines an extension to the vCard Extensions to WebDAV (CardDAV) protocol that allows a server to expose a directory as a read-only address book collection.
Also see CalConnect CC/R 1104:2011.
6. WebDAV
6.1. Base Standards
6.1.1. HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV) RFC 4918
Web Distributed Authoring and Versioning (WebDAV) consists of a set of methods, headers, and content-types ancillary to HTTP/1.1 for the management of resource properties, creation and management of resource collections, URL namespace manipulation, and resource locking (collision avoidance).
6.2. Additional and Extensions
6.2.1. Binding Extensions to WebDAV RFC 4842
This specification defines bindings, and the BIND method for creating multiple bindings to the same resource. Creating a new binding to a resource causes at least one new URI to be mapped to that resource. Servers are required to ensure the integrity of any bindings that they allow to be created.
6.2.2. Extended MKCOL for Web Distributed Authoring and Versioning (WebDAV) RFC 5689
This specification extends the Web Distributed Authoring and Versioning (WebDAV) MKCOL (Make Collection) method to allow collections of arbitrary resource-type to be created and to allow properties to be set at the same time.
6.2.3. Quota and Size Properties for Distributed Authoring and Versioning (DAV) Collections RFC 4331
This document discusses the properties and minor behaviors needed for clients to interoperate with quota (size) implementations on WebDAV repositories.
6.2.4. Using POST to Add Members to WebDAV Collectons RFC 5995
This specification defines a discovery mechanism through which servers can advertise support for POST requests with the aforementioned “add collection member” semantics.
6.2.5. Versioning Extensions to WebDAV RFC 3253
This document specifies a set of methods, headers, and resource types that define the WebDAV (Web Distributed Authoring and Versioning) versioning extensions to the HTTP/1.1 protocol.
6.2.6. Web Distributed Authoring and Versioning (WebDAV) SEARCH RFC 5323
This document specifies a set of methods, headers and properties composing WebDAV SEARCH, an application of the HTTP/1.1 protocol to efficiently search for DAV resources based upon a set of client- supplied criteria.
6.2.7. WebDAV Access Control Protocol RFC 3744
This specification extends the Web Distributed Authoring and Versioning (WebDAV) Protocol to support the server-side ordering of collection members.
6.2.8. WebDAV Current Principal Extension RFC 5397
This specification defines a new WebDAV property that allows clients to quickly determine the principal corresponding to the current authenticated user.
6.2.9. WebDAV Ordered Collections Protocol RFC 3648
This specification extends the Web Distributed Authoring and Versioning (WebDAV) Protocol to support the server-side ordering of collection members.
6.3. Work in Progress
6.3.1. Collection Synchronization for WebDAV
This specification defines an extension to WebDAV that allows efficient synchronization of the contents of a WebDAV collection.
7. Related
7.1. Base Standards
7.1.1. Date and Time on the Internet: Timestamps RFC 3339
This document defines a date and time format for use in Internet protocols that is a profile of the ISO 8601 standard for representation of dates and times using the Gregorian calendar.
7.3. Work in Progress
7.3.1. Portable Contacts
The Portable Contacts specification is designed to make it easier for developers to give their users a secure way to access the address books and friends lists they have built up all over the web. Specifically, it seeks to create a common access pattern and contact schema that any site can provide, well-specified authentication and access rules, standard libraries that can work with any site, and absolutely minimal complexity, with the lightest possible toolchain requirements for developers.
7.3.2. Timezone Service Protocol
This document defines a timezone service protocol that allows reliable, secure and fast delivery of timezone information to client systems such as calendaring and scheduling applications or operating systems.
7.3.3. Timezone XML Specification
This specification describes a format for describing timezone information for software and services.
7.3.4. WS-Calendar
WS-Calendar is an OASIS cross-domain standard for passing schedule and interval information between and within services.
Bibliography
[1] IETF RFC 2739, SMALL, T., D. HENNESSY, F. DAWSON and Internet Engineering Task Force. Calendar Attributes for vCard and LDAP. 2000. RFC Publisher. https://www.rfc-editor.org/info/rfc2739.
[2] IETF RFC 3253, CLEMM, G., J. AMSDEN, T. ELLISON, C. KALER, J. WHITEHEAD and Internet Engineering Task Force. Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning). 2002. RFC Publisher. https://www.rfc-editor.org/info/rfc3253.
[3] IETF RFC 3339, KLYNE, G., C. NEWMAN and Internet Engineering Task Force. Date and Time on the Internet: Timestamps. 2002. RFC Publisher. https://www.rfc-editor.org/info/rfc3339.
[4] IETF RFC 3648, WHITEHEAD, J. and Internet Engineering Task Force. Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol. 2003. RFC Publisher. https://www.rfc-editor.org/info/rfc3648.
[5] IETF RFC 3744, CLEMM, G., J. RESCHKE, E. SEDLAR, J. WHITEHEAD and Internet Engineering Task Force. Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol. 2004. RFC Publisher. https://www.rfc-editor.org/info/rfc3744.
[6] IETF RFC 4331, KORVER, B., L. DUSSEAULT and Internet Engineering Task Force. Quota and Size Properties for Distributed Authoring and Versioning (DAV) Collections. 2006. RFC Publisher. https://www.rfc-editor.org/info/rfc4331.
[7] IETF RFC 4791, DABOO, C., B. DESRUISSEAUX and L. DUSSEAULT. Calendaring Extensions to WebDAV (CalDAV). 2007. RFC Publisher. https://www.rfc-editor.org/info/rfc4791.
[8] IETF RFC 4842, MALIS, A., P. PATE, D. ZELIG and Internet Engineering Task Force. Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP). 2007. RFC Publisher. https://www.rfc-editor.org/info/rfc4842.
[9] IETF RFC 4918, Internet Engineering Task Force (committee). HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV). 2007. RFC Publisher. https://www.rfc-editor.org/info/rfc4918.
[10] IETF RFC 5323, REDDY, S., J. DAVIS and A. BABICH. Web Distributed Authoring and Versioning (WebDAV) SEARCH. 2008. RFC Publisher. https://www.rfc-editor.org/info/rfc5323.
[11] IETF RFC 5333, MAHY, R., B. HOENEISEN and Internet Engineering Task Force. IANA Registration of Enumservices for Internet Calendaring. 2009. RFC Publisher. https://www.rfc-editor.org/info/rfc5333.
[12] IETF RFC 5397, SANCHEZ, W. and C. DABOO. WebDAV Current Principal Extension. 2008. RFC Publisher. https://www.rfc-editor.org/info/rfc5397.
[13] IETF RFC 5545, Internet Engineering Task Force (committee). Internet Calendaring and Scheduling Core Object Specification (iCalendar). 2009. RFC Publisher. https://www.rfc-editor.org/info/rfc5545.
[14] IETF RFC 5546, Internet Engineering Task Force (committee). iCalendar Transport-Independent Interoperability Protocol (iTIP). 2009. RFC Publisher. https://www.rfc-editor.org/info/rfc5546.
[15] IETF RFC 5689, DABOO, C. and Internet Engineering Task Force. Extended MKCOL for Web Distributed Authoring and Versioning (WebDAV). 2009. RFC Publisher. https://www.rfc-editor.org/info/rfc5689.
[16] IETF RFC 5995, RESCHKE, J. Using POST to Add Members to Web Distributed Authoring and Versioning (WebDAV) Collections. 2010. RFC Publisher. https://www.rfc-editor.org/info/rfc5995.
[17] IETF RFC 6047, Internet Engineering Task Force (committee). iCalendar Message-Based Interoperability Protocol (iMIP). 2010. RFC Publisher. https://www.rfc-editor.org/info/rfc6047.
[18] IETF RFC 6321, DABOO, C., M. DOUGLASS and S. LEES. xCal: The XML Format for iCalendar. 2011. RFC Publisher. https://www.rfc-editor.org/info/rfc6321.
[19] IETF RFC 6350, PERREAULT, S. and Internet Engineering Task Force. vCard Format Specification. 2011. RFC Publisher. https://www.rfc-editor.org/info/rfc6350.
[20] IETF RFC 6351, PERREAULT, S. and Internet Engineering Task Force. xCard: vCard XML Representation. 2011. RFC Publisher. https://www.rfc-editor.org/info/rfc6351.
[21] IETF RFC 6352, DABOO, C. and Internet Engineering Task Force. CardDAV: vCard Extensions to Web Distributed Authoring and Versioning (WebDAV). 2011. RFC Publisher. https://www.rfc-editor.org/info/rfc6352.
[22] Internet-Draft draft-daboo-calendar-availability-05, DABOO, Cyrus and Mike DOUGLASS. Calendar Availability. 2014. https://datatracker.ietf.org/doc/html/draft-daboo-calendar-availability-05.
[23] Internet-Draft draft-douglass-calendar-extension-06, DOUGLASS, Michael. Event Publishing Extensions to iCalendar. 2016. https://datatracker.ietf.org/doc/html/draft-douglass-calendar-extension-06.
[24] Internet-Draft draft-desruisseaux-ischedule-01, DABOO, Cyrus and Bernard DESRUISSEAUX. Internet Calendar Scheduling Protocol (iSchedule). 2010. https://datatracker.ietf.org/doc/html/draft-desruisseaux-ischedule-01.
[25] Internet-Draft draft-douglass-link-extension-01, DOUGLASS, Mike. Link Extension to Icalendar. 2011. https://datatracker.ietf.org/doc/html/draft-douglass-link-extension-01.
[26] iCalendar mask UIDs, https://svn.macosforge.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/icalendar-maskuids.txt
[27] Internet-Draft draft-cal-resource-schema-06, JOY, Ciny, Cyrus DABOO and Mike DOUGLASS. Schema for representing resources for calendaring and scheduling services. 2011. https://datatracker.ietf.org/doc/html/draft-cal-resource-schema-06.
[28] Internet-Draft draft-daboo-icalendar-extensions-09, DABOO, Cyrus. New Properties for iCalendar. 2014. https://datatracker.ietf.org/doc/html/draft-daboo-icalendar-extensions-09.
[29] Internet-Draft draft-daboo-valarm-extensions-05, DABOO, Cyrus and Kenneth MURCHISON. VALARM Extensions for iCalendar. 2019. https://datatracker.ietf.org/doc/html/draft-daboo-valarm-extensions-05.
[30] CalDAV CTag, http://trac.calendarserver.org/browser/CalendarServer/trunk/doc/Extensions/caldav-ctag.txt
[31] CalDAV Proxy, https://svn.macosforge.org/repository/calendarserver/CalendarServer/trunk/doc/Extensions/caldav-proxy.txt
[32] Internet-Draft draft-daboo-srv-caldav-10, DABOO, Cyrus. Locating Services for Calendaring Extensions to WebDAV (CalDAV) and vCard Extensions to WebDAV (CardDAV). 2010. https://datatracker.ietf.org/doc/html/draft-daboo-srv-caldav-10.
[33] Internet-Draft draft-desruisseaux-caldav-sched-10, DABOO, Cyrus and Bernard DESRUISSEAUX. CalDAV Scheduling Extensions to WebDAV. 2011. https://datatracker.ietf.org/doc/html/draft-desruisseaux-caldav-sched-10.
[34] hCard, http://microformats.org/wiki/hcard
[35] Internet-Draft draft-daboo-vcard-service-type-00, DABOO, Cyrus. vCard: Service Type Parameter. 2010. https://datatracker.ietf.org/doc/html/draft-daboo-vcard-service-type-00.
[36] Internet-Draft draft-daboo-carddav-directory-gateway-02, DABOO, Cyrus. CardDAV Directory Gateway Extension. 2010. https://datatracker.ietf.org/doc/html/draft-daboo-carddav-directory-gateway-02.
[37] Internet-Draft draft-daboo-webdav-sync-08, DABOO, Cyrus and Arnaud QUILLAUD. Collection Synchronization for Web Distributed Authoring and Versioning (WebDAV). 2012. https://datatracker.ietf.org/doc/html/draft-daboo-webdav-sync-08.
[38] Portable Contacts, http://portablecontacts.net/draft-spec.html
[39] Internet-Draft draft-douglass-timezone-service-11, DOUGLASS, Mike and Cyrus DABOO. Timezone Service Protocol. 2014. https://datatracker.ietf.org/doc/html/draft-douglass-timezone-service-11.
[40] Internet-Draft draft-douglass-timezone-xml-00, DOUGLASS, Mike and Cyrus DABOO. Timezone XML Specification. 2010. https://datatracker.ietf.org/doc/html/draft-douglass-timezone-xml-00.
[41] WS-Calendar, http://docs.oasis-open.org/ws-calendar/ws-calendar/v1.0/ws-calendar-1.0-spec.html
[42] CalConnect CC/S 0903:2009, CalConnect, ERIC YORK and CalConnect. Freebusy Read URL. First edition. 2009. CalConnect.
[43] CalConnect CC/R 1012:2010, CalConnect and CalConnect. An Introduction to Internet Calendaring and Scheduling. First edition. 2011. CalConnect.
[44] CalConnect CC/R 1011:2010, CalConnect and CalConnect. CalWS-Rest — Restful Web Services Protocol for Calendaring. First edition. 2010. CalConnect.
[45] CC/R 1102, [NO INFORMATION AVAILABLE]
[46] CalConnect CC/R 1104:2011, CalConnect and CalConnect. Index to Calendaring and Scheduling Standards. Second edition. 2011. CalConnect.
[47] hCalendar, https://microformats.org/wiki/hcalendar