[uf-dev] Parsing class=value-title

Ben Ward lists at ben-ward.co.uk
Wed Mar 10 11:14:26 PST 2010

Hi Toby,

On 10 Mar 2010, at 06:08, Toby Inkster wrote:

> However, from the Wiki...
> http://microformats.org/wiki/value-class-pattern#Parsing_machine-data_value-title
>> Microformat specifications must explicitly state which properties
>> may be used with this extension of the value-class-pattern.
> Given that none do, it seems that class="value-title" will never be
> legitimately encountered, so I can cross it off as "done" with no code
> changes.
> Am I right? If not, why not?

The rationale went like this: We were designing a pattern that has a difficult relationship with our principals of DRY and invisible data, but comes in reaction to actual publisher and parser experience. We didn't want to create a pattern that enabled a generic hidden-data mechanism, and so I wrote in that clause, which is supposed to ensure that each microformat vocabulary identifies the applicable date, duration and any other fixed-format fields that class=value-title may be parsed with.

This was probably an error, since the revision cycle for other specs is too infrequent.

However, further along in the documentation is this:

> This document post-dates other microformat specifications, such that they may not yet indicate which properties permit use of this pattern. In the interim, the following types of properties should allow the value-title pattern.
> 	• ISO8601 date, datetime, timezone, and duration values
> 	• Enumerated values (such as the hCard tel/email/adr 'type' subproperties)
> 	• Co-ordinates (such as the geo 'latitude' and 'longitude' properties)
> 	• Telephone number properties (e.g. the hCard 'tel' property)
> The [[machine-data]] page has documentation of some of the properties of some specs which experience has shown need a solution like the value-title pattern.

So, value-title is applied retroactively via the properties documented on <http://microformats.org/wiki/machine-data>, and has been implemented by other parsers. Google have added support for parsing value-title (albeit without any property restrictions), and also document its use in hCalendar for their Rich Snippets app.

I agree the current documentation is misleading and inaccurate, so I'll give that a tweak.


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