last-modified-brainstorming
"Last-modified" Brainstorming
Towards the development of a last-modified microformat.
Purpose
To specify the date of publication and the date of modification of a web page (or a part thereof) in a way that is both readable for humans and machines.
Authors
Semantics
Since both Atom and HTTP define the last-modified date (or its equivalent) as a "user-defined" value, this microformat should have the same semantics. In other words, the value should represent the last instance that the resource was changed in a way deemed significant to the publisher/author, which is not neccessarily the same as a file-system modified date-time. --RyanKing
Possible class names
Class name considerations
Class names for the date of publication
- “date”: Dublin Core
- “published”: Atom
- “dtpublished”: As suggested by Paul Bryson for hAtom. See http://microformats.org/discuss/mail/microformats-discuss/2005-December/002520.html
Class names for the date of the last modification
- “last-modified”: “Last-Modified” used by HTTP 1.0 and 1.1, hCalendar
- “modified”: Dublin Core
- “updated”: Atom 1.0 syndication specification
Different class name for page specific and item specific dates?
For example “page-last-modified” is used to indicate the last modification date of a page and “last-modified” for the last modification date of a specific item*. However, this seems to be not a good idea. Other microformats leave it to the parser to pick the scope of the element, e.g. rel-tag.
See http://microformats.org/discuss/mail/microformats-discuss/2005-August/000726.html for a related discussion.
* This specific item is marked-up with a microformat, e.g: a microformat to describe blog posts may use “last-modified” to indicate when a blog post was last modified.
Possible date formats
Issues
- 2006-02-13 raised by Eron Wright
- Last-modified dates are unsuitable as version numbers. As the HTTP 1.1 spec mentions, dates lack fidelity and are difficult to generate for dynamic content. A better solution is to use an opaque string, as HTTP does with the ETag header. Indeed, If-Modified-Since is deprecated.
Proposal (2nd, strawman)
Purpose
Many web pages (and parts thereof) state their publication and/or modification date in a human readable way. This proposed microformat specifies how this can be done in a fashion that is both human- and machine-readable.
Specifying the date of publication
The date of publication is enclosed by <abbr class="date-published1" title="Date in ISO format">Date in arbitrary format</abbr>, e.g:
<p>Published on <abbr class="date-published1" title="2005-12-29T14:39:12+0100">Thursday, December 29, 2005 02:39:12 a.m.</abbr>.</p>.
Specifying the date of modification
The date of modification is enclosed by <abbr class="date-modified1" title="Date in ISO format">Date in arbitary format</abbr>, e.g:
<p>Last modified on <abbr class="date-modified1" title="2005-12-29T14:39:12+0100">Thursday, December 29, 2005 02:39:12 a.m.</abbr>.</p>.
If no date of modification is present the parsers MAY use the date of publication as the date of the last modification.
<del> and <ins>
Authors MAY also use <del> and <ins> to denote the date of
modification, e.g:
<del class="date-modified1" datetime="2005-12-29T14:39:12+0100">wrong words</del>.
The class value "date-modified1" is implied for every <del> and <ins>
element which has a datetime attribute.
Multiple dates in a page (or a part thereof)
If multiple dates of publication are present on a page (or a part thereof) the youngest date SHOULD be interpreted as the date of publication.
If multiple dates of modification are present on a page (or a part thereof) the oldest date SHOULD be interpreted as the date of modification.
1 This class name is just a placeholder which will be replaced once we know a suitable name.