Some issues include:
- what domain to use? Candidates include:
- what about versioning? How to keep in sync with the wiki and test materials?
- what profile URI to use for combinations, such as hCard 1.0 and hCalendar 1.0?
- note HTML4.01 states "that one or more meta data profiles, [are] separated by white space"; though it's simpler for authors if they can just use one profile URI.
- More profiles are needed.
One proposal is: use www.w3.org, following W3C namespace policy. As to versioning, change the profile whenever the wiki changes (within some reasonable latency, say, a couple weeks or a month). For example: an hCard Profile at w3.org, and discussion: an hCard profile that seems to work with GRDDL.
Due to an ambiguous wording of the HTML specs, HTMLTidy (and other tools?) give "Warning: <head> escaping malformed URI reference"
when more than one profile is used (e.g.
<head profile="http://www.ietf.org/rfc/rfc2731.txt http://www.w3.org/2006/03/hcard">
). However, this is valid according to the W3C HTML validator.