hCalendar 1.0 - Microformats Wiki
hCalendar 1.0
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h-event
Tantek Çelik
Editor
Author
Brian Suda
Author
hCalendar
is a simple, open format for publishing events on the web, using a 1:1 representation of iCalendar (
RFC2445
) VEVENT properties and values in HTML. hCalendar is one of several open
microformat
standards suitable for embedding data in HTML/HTML5, and Atom/RSS/XHTML or other XML.
and
patents
statements apply. See
acknowledgments
Contents
Example
Status
2.1
Available languages
2.2
Errata and Updates
Introduction
Semantic XHTML Design Principles
Format
5.1
In General
5.2
Root Class Name
5.3
Properties and Sub-properties
5.4
Property List
5.5
Profile
5.6
More Semantic Equivalents
5.7
Singular vs. Plural Properties
5.7.1
Plural Properties Singularized
5.8
Human vs. Machine readable
Examples
6.1
Meeting Example
6.2
XYZ Project Review
6.3
More Examples
Examples in the wild
Implementations
Articles
10
Buttons
11
12
Patents
13
References
13.1
Normative References
13.2
Informative References
13.2.1
Specifications That Use hCalendar
13.2.2
Related Work
14
Inspiration and Acknowledgments
15
Related Reading
16
Related Pages
17
Translations
Example
Here is a simple prose event:
The microformats.org site was launched on 2005-06-20 at the Supernova Conference in San Francisco, CA, USA.
marked up with hCalendar
span
class
"vevent"
span
class
"summary"
The microformats.org site was launched
span
on
span
class
"dtstart"
2005-06-20
span
at the Supernova Conference
in
span
class
"location"
San Francisco, CA, USA
span
span
Want to get started with writing an
hCalendar
event?
Use the
hCalendar creator
to write up an event and publish it, or follow the
hCalendar authoring tips
to add hCalendar markup to your page of upcoming events or events you mention in blog posts, wikis, etc.
Status
hCalendar 1.0 is a microformats.org specification. Public discussion on hCalendar takes place on
hcalendar-feedback
, the #microformats
irc
channel on irc.freenode.net, and
microformats-discuss mailing list
Available languages
The English version of this specification is the only normative version. For translations of this document see the
#translations
section.
Errata and Updates
Known errors and issues in this specification are corrected in
resolved
and
closed
issues. Please check there before reporting
issues
Note in particular the
dtend-issue
which affects end dates. Implementations
SHOULD
implement the issue resolution ASAP and
test it
The hCalendar 1.0.1 update is currently under development and incorporates known errata corrections as well as the
value-class-pattern
Introduction
The iCalendar standard (
RFC2445
), has been broadly interoperably implemented (e.g. Apple's "iCal" application built into MacOSX).
In addition, bloggers often discuss events on their blogs -- upcoming events, writeups of past events, etc. With just a tad bit of structure, bloggers can discuss events in their blog(s) in such a way that spiders and other aggregators can retrieve such events, automatically convert them to iCalendar, and use them in any iCalendar application or service.
This specification introduces the
hCalendar
format, which is a 1:1 representation of the aforementioned iCalendar standard, in semantic HTML. Bloggers can both embed hCalendar events directly in their web pages, and style them with CSS to make them appear as desired. In addition, hCalendar enables applications to retrieve information about such events directly from web pages without having to reference a separate file.
The key words "
MUST
", "
MUST NOT
", "
REQUIRED
", "
SHALL
", "
SHALL NOT
", "
SHOULD
", "
SHOULD NOT
", "
RECOMMENDED
", "
MAY
", and "
OPTIONAL
" in this document are to be interpreted as described in
RFC 2119
Semantic XHTML Design Principles
Note: the Semantic XHTML Design Principles were written primarily within the context of developing
hCard
and
hCalendar
, thus it may be easier to understand these principles in the context of the
hCard design methodology
(i.e. read that first).
Tantek
XHTML is built on XML, and thus XHTML based formats can be used not only for convenient display presentation, but also for general purpose data exchange. In many ways, XHTML based formats exemplify the best of both HTML and XML worlds. However, when building XHTML based formats, it helps to have a guiding set of principles.
Reuse the schema (names, objects, properties, values, types, hierarchies, constraints) as much as possible from pre-existing, established, well-supported standards by reference. Avoid restating constraints expressed in the source standard. Informative mentions are ok.
For types with multiple components, use nested elements with class names equivalent to the names of the components.
Plural components are made singular, and thus multiple nested elements are used to represent multiple text values that are comma-delimited.
Use the most accurately precise
semantic XHTML
building block for each object etc.
Otherwise use a generic structural element (e.g.
or
), or the appropriate contextual element (e.g. an
inside a
or
).
Use class names based on names from the original schema, unless the semantic XHTML building block precisely represents that part of the original schema. If names in the source schema are case-insensitive, then use an all lowercase equivalent. Components names implicit in prose (rather than explicit in the defined schema) should also use lowercase equivalents for ease of use. Spaces in component names become dash '-' characters.
Finally, if the format of the data according to the original schema is too long and/or not human-friendly, use
instead of a generic structural element, and place the literal data into the 'title' attribute (where abbr expansions go), and the more brief and human readable equivalent into the element itself. Further informative explanation of this use of
Human vs. ISO8601 dates problem solved
For practical implementations, it should be noted that Internet Explorer's support for styling
elements is poor, and may require wrapper elements.
Format
In General
The iCalendar standard (
RFC2445
) forms the basis of hCalendar.
Note: the editor and authors of this specification are tracking the
"iCal-Basic" effort
and intend to base the core hCalendar profile on iCal-Basic. See references for a link to the current draft.
The basic format of hCalendar is to use iCalendar object/property names in lower-case for class names, and to map the nesting of iCalendar objects directly into nested XHTML elements.
Root Class Name
The root class name for hCalendar is "vcalendar". An element with a class name of "vcalendar" is itself called an
hCalendar
The root class name for events is "vevent". An element with a class name of "vevent" is itself called an
hCalendar event
For authoring convenience, both "vevent" and "vcalendar" are treated as root class names for parsing purposes. If a document contains elements with class name "vevent" but not "vcalendar", the entire document has an implied "vcalendar" context.
vevent
should be considered required for each event listing.
Properties and Sub-properties
The properties of an hCalendar are represented by elements inside the hCalendar. Elements with class names of the listed properties represent the values of those properties. Some properties have sub-properties, and those are represented by elements inside the elements for properties.
Property List
hCalendar properties (sub-properties in parentheses like this)
Required:
dtstart
ISO date
summary
Optional:
location
url
dtend (ISO date), duration (ISO date duration)
rdate, rrule
category, description
uid
geo (latitude, longitude)
attendee (partstat, role), contact, organizer
attach
status
... editor's note: this list is incomplete (an incomplete list is better than no list) and is being currently edited from RFC2445 to here. The above list of properties are those that are often used in hCalendar on the web.
Profile
The hCalendar XMDP profile is at
Content that uses hCalendar
SHOULD
reference this profile, e.g.
head
profile
"http://microformats.org/profile/hcalendar"
or
link
rel
"profile"
href
"http://microformats.org/profile/hcalendar"
or
This content uses
rel
"profile"
href
"http://microformats.org/profile/hcalendar"
hCalendar
Content may combine the above methods as well.
More Semantic Equivalents
For some properties there is a more semantic equivalent, and therefore they get special treatment, e.g.:
URL
in iCalendar becomes
...
inside the element with
class="vevent"
in hCalendar.
ATTENDEE
CONTACT
, and
ORGANIZER
in iCalendar
MAY
be represented by an
hCard
in hCalendar .
A named
LOCATION
(potentially with an address and/or geo) in iCalendar
MAY
be represented by a nested
hCard
in hCalendar. Similarly, an address
LOCATION
MAY
be represented by an
adr
, and a geo (latitude and longitude)
LOCATION
may be represented by a
geo
UID
in iCalendar simply becomes another semantic applied to a specific URL for an hCalendar event.
ATTACH
in iCalendar becomes an img or object element (where the value is stored ito / retrieved from the 'src' or 'data' attributes respectively). An
...
may also be used, in which case the 'href' attribute is used for the property value.
Singular vs. Plural Properties
For properties which are singular (e.g. "N" and "FN" from vCard), the first descendant element with that class
SHOULD
take effect, any others being ignored.
For properties which can be plural (e.g. "TEL" from vCard), each class instance
SHOULD
create a instance of that property. Plural properties with subtypes (e.g. TEL with WORK, HOME, CELL from vCard) can be optimized to share a common element for the property itself, with each instance of subtype being an appropriately classed descendant of the property element.
Plural Properties Singularized
Since plural property names become their singular equivalents, even if the original plural property permitted only a single value with multiple components, those multiple components are represented each with their own singularly named property and the the property is effectively multivalued and subject to the above treatment of multivalued properties.
Human vs. Machine readable
If an
element is used for a property, then the '
title
' attribute of the
element is the value of the property, instead of the contents of the element, which instead provide a human presentable version of the value. This specification recommends that such
elements be used for the following iCalendar properties:
DTSTART, DTEND, DURATION, RDATE, RRULE
Examples
Here is a sample multiple-day event in an iCalendar:
BEGIN:VCALENDAR
PRODID:-//XYZproduct//EN
VERSION:2.0
BEGIN:VEVENT
URL:http://conferences.oreillynet.com/pub/w/40/program.html
DTSTART:20051005
DTEND:20051008
SUMMARY:Web 2.0 Conference
LOCATION:Argent Hotel\, San Francisco\, CA
END:VEVENT
END:VCALENDAR
and an equivalent event in hCalendar format with various elements optimized appropriately. See
hcalendar-example1-steps
for the derivation.
div
class
"vevent"
class
"url"
href
"http://conferences.oreillynet.com/pub/w/40/program.html"
span
class
"summary"
Web 2.0 Conference
span
abbr
class
"dtstart"
title
"2005-10-05"
October 5
abbr
abbr
class
"dtend"
title
"2005-10-07"
abbr
at the
span
class
"location"
Argent Hotel, San Francisco, CA
span
div
which could be displayed as:
Web 2.0 Conference
October 5
at the
Argent Hotel, San Francisco, CA
Note 1: that this is a
live
hCalendar microformat, which will be found on this page by parsers.
Note 2: This example used to have "2005-10-08" as the value of the dtend, but per the resolution to the
dtend-issue
, has been changed to "2005-10-07" in order to encourage publishers/implementers to update their markup/code immediately and
test it
Note 3: Note that the iCalendar in the first part of the example has the code
DTEND:20051008
. That "8" is not a typo. iCalendar uses
exclusive
whole end dates (DTEND values) and thus requires that the DTEND value be set to a whole day
after
what content publishers visibly display as the ending date of an event. iCalendar's exclusive end dates convention has shown to be
problematic and confusing
for content authors and publishers. Thus per the resolution to the
dtend-issue
, in hCalendar, the end date is stated exactly as existing events publish visible end dates to humans, with an
inclusive
end date (dtend property value), in this example, 2005-10-07.
Meeting Example
The following
example
specifies a scheduled meeting that begins
at 8:30 AM EST on March 12, 1998 and ends at 9:30 AM EST on March 12,
1998.
BEGIN:VCALENDAR
BEGIN:VEVENT
UID:guid-1.host1.com
DTSTAMP:19980309T231000Z
DESCRIPTION:Project XYZ Review Meeting
SUMMARY:XYZ Project Review
DTSTART:19980312T133000Z
DTEND:19980312T143000Z
LOCATION:1CP Conference Room 4350
END:VEVENT
END:VCALENDAR
The equivalent in hCalendar:
div
class
"vevent"
h3
class
"summary"
XYZ Project Review
h3
class
"description"
Project XYZ Review Meeting
To be held on
span
class
"dtstart"
abbr
class
"value"
title
"1998-03-12"
the 12th of March
abbr
from
span
class
"value"
8:30am
span
abbr
class
"value"
title
"-0500"
EST
abbr
span
until
span
class
"dtend"
span
class
"value"
9:30am
span
abbr
class
"value"
title
"-0500"
EST
abbr
span
Location:
span
class
"location"
1CP Conference Room 4350
span
>small
Booked by:
span
class
"uid"
guid-1.host1.com
span
on
span
class
"dtstamp"
abbr
class
"value"
title
"1998-03-09"
the 9th
abbr
at
span
class
"value"
6:00pm
span
span
small
div
This could be displayed as:
XYZ Project Review
Project XYZ Review Meeting
To be held on
the 12th of March from 8:30am EST
until
9:30am EST
Location:
1CP Conference Room 4350
Booked by:
guid-1.host1.com
on
the 9th at 6:00pm
Note 1: The product information is not necessary since hCalendar is an interchange format. When transforming hCalendar back into iCalendar, the transforming engine should add its own product ID.
Note 2: A surrounding
element is optional, and is left out as such. It is optional since the context of a vcalendar is implied when a vevent is encountered. The implied context/scope is that of the document. Authors may explicitly use elements with class="vcalendar" to wrap sets of vevents that all belong to the same calendar, e.g. when publishing multiple calendars on the same page.
Note 3: The version information is unnecessary in hCalendar markup directly since the version will be defined by the profile of hCalendar that is used/referred to in the 'profile' attribute of the element.
Note 4:
ISO8601
datetimes (required by iCalendar) are not very human friendly. In addition, the year is often understood implicitly by humans from the context. Thus the
value-class-pattern
and
elements are used to simultaneously provide human friendly dates and/or times in the visible contents of the element, while placing the respective machine parsable comprehensive ISO8601 dates and times in the 'title' attribute when necessary. Per the
value-class-pattern
, separate dates and times
SHOULD
be used by authors rather than a full ISO8601 datetime, for better readability and listenability.
Note 5: Per the
dtend-issue
resolution, DTEND dates are provided as humans expecte them to be (consistent with what day an event ends on), rather than iCalendar's confusing definition (the day after). Thus hCalendar processors which produce iCalendar must make the transformation, which is to treat a whole hCalendar
dtend
end date as *inclusive*, and convert it to an *
exclusive DTEND
* end date when producing iCalendar.
Note 6: The location in this example contains implicit structure (venue name, city, state) which could be marked up explicitly as an
hCard
. See
hCalendar brainstorming: hCard locations
for a informative explanation of how to do this.
More Examples
See
hCalendar examples
for more examples, including examples from iCalendar RFC 2445 converted into hCalendar.
Examples in the wild
This section is
informative
. The number of hCalendar examples in the wild has expanded far beyond the capacity of being kept inline in this specification. They have been moved to a
separate page
See
hCalendar Examples in the wild
Implementations
This section is
informative
. The number of hCalendar implementations has also expanded beyond the capacity of keeping them inline. They have been moved to a
separate page
See
hCalendar Implementations
Articles
This section is
informative
See:
hcalendar-articles
Buttons
This section is
informative
. Don't forget that you can add one of our
buttons
to the page, to indicate the presence of hCalendar microformats. For example:
. If you can link it back to this page (or even page on your website, about your use of the microformat), so much the better!
Per the public domain release on the authors' user pages (
Tantek Çelik
Brian Suda
) this specification is released into the public domain.
Public Domain Contribution Requirement
. Since the author(s) released this work into the public domain, in order to maintain this work's public domain status, all contributors to this page agree to release their contributions to this page to the public domain as well. Contributors may indicate their agreement by adding the
public domain release template
to their user page per the
Voluntary Public Domain Declarations instructions
. Unreleased contributions may be reverted/removed.
Patents
This specification is subject to a royalty free patent policy, e.g. per the
W3C Patent Policy
, and IETF
RFC3667
RFC3668
References
Normative References
XHTML 1.0 SE
hCard
iCalendar RFC2445
RFC 2119
ISO8601
Informative References
This section is
informative
CSS1
hCalendar term introduced and defined on the Web, 20040930
FOO Camp 2004 HTML For Calendars presentation, 20040911
FOO Camp 2004 Simple Semantic Formats presentation, 20040910
iCal-Basic (latest)
(draft 04)
W3C Note on Date and Time Formats
Internet Mail Consortium Personal Data Interchange vCard and vCalendar
Contributed from
Specifications That Use hCalendar
hReview
Related Work
IETF-calsify archives
RFC2445 Issues List
CALSIFY WG Links And Resources
Inspiration and Acknowledgments
Thanks to:
Adam Bosworth for leading the
FOO Camp 2004 HTML For Calendars presentation
which brought together a critical mass of interested parties.
Related Reading
This section is
informative
Some
further reading
on the broader topic of calendars and calendaring formats.
jwz - Hula
(required reading)
Groupware Bad by Jamie Zawinski
crystalizes the reason for hCalendar (
emphasis
added):
Right now people can do that by publishing .ics files, but it's not trivial to do so, and it's work on the part of other people to look at them.
If it's not HTML hanging off our friend's home page that can be viewed in any browser on a public terminal in a library, the bar to entry is too high and it's useless.
Related Pages
hCalendar
- specification
hCalendar intro
- plain English introduction
hCalendar authoring
- learn how to add hCalendar markup to your existing events.
hCalendar creator
hCalendar creator feedback
) - create your own hCalendar events.
hCalendar cheatsheet
- hCalendar properties
hCalendar examples in the wild
- an on-going list of websites which use hCalendars.
hCalendar implementations
- websites or tools which either generate or parse hCalendars
hCalendar FAQ
- If you have any questions about hCalendar, check here.
hCalendar parsing
- normative details of how to parse hCalendar.
hCalendar profile
- the XMDP profile for hCalendar
hCalendar singular properties
- an explanation of the list of singular properties in hCalendar.
hCalendar tests
- a wiki page with actual embedded hCalendar events to try parsing.
hCalendar "to do"
- jobs to do
hCalendar advocacy
- encourage others to use hCalendar.
iCalendar implementations
This specification is a work in progress. As additional aspects are discussed, understood, and written, they will be added. These thoughts, issues, and questions are kept in separate pages.
hCalendar Brainstorming
- brainstorms and other explorations relating to hCalendar
hCalendar issues
- issues with the specification
Wikipedia article on hCalendar
Translations
Read the hCalendar specification in additional
languages
(French)
(Japanese)
Polski
(Polish)
Русский
(Russian)
Retrieved from "
Categories
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