[uf-dev] Preventing false positives

Toby A Inkster mail at tobyinkster.co.uk
Sat May 3 13:50:24 PDT 2008

Dan Brickley wrote:

> Is 'singular property' accepted Microformat-community terminology? (or
> just an obvious/sensible phrase). Is there any machine-readable
> representation of which microformat properties are singular?

The terms used in the hCard spec are "singular property" and "plural  
property". A list of the singular properties for hCard can be found at:


The hCard spec is rather casual about such matters -- it's just  
described in prose. Some of the newer microformats include property  
lists marked up as nested unordered HTML lists with Perl-like  
quantifiers, such as "{1}" = must occur exactly once; "*" = optional,  
may occur more than once; "+" = optional, may only occur once; etc.  
These could theoretically be parsed mechanically, but that wouldn't  
be enough to fully automate supporting new microformats, as there's  
still the matter of content models (e.g. should something be parsed  
as a link, or as a string).

> Is there a microformal word for the inverse of this concept:  
> properties
> that have at most one proper value, for anything they apply to? In  
> examples of this (we call it an "Inverse Functional Property") include
> "homepage", "weblog", "openid", "tipjar", "jabberID",  
> "mbox_sha1sum"...

The UID property of hCard and hCalendar are in effect inverse  
functional properties. (Indeed my parser implements them as such. If  
two hCalendar events exist which share a UID, they'll be conflated  
into the same event in the output.)

PS: Dan, did you get my e-mail on 27 April? I sent it to your  
rdfweb.org address -- not sure if that's still valid?

Toby A Inkster
<mailto:mail at tobyinkster.co.uk>

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