This is a metadata profile a la section 6.12 (Link types) of the HTML 4.0 specification:-
Authors may wish to define additional link types not described in this specification. If they do so, they should use a profile to cite the conventions used to define the link types.
By referring to the URI http://purl.org/net/uriprofile/,
you are associating a profile with your HTML / XHTML that allows you to use
the keword "meta" as a link type in your
Use of this URI as an XHTML head@profile extends the allowed HTML link types from the ones in the specification to cover the keyword "meta" as well, except where this conflicts with link types defined in any other meta data profile.
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" > <head profile="http://purl.org/net/uriprofile/"> <title>Page Title</title> <link rel="meta" href="a.rdf" /> </head> <body> [...] </body> </html>
From the HTML 4.01 Recommendation:-
The profile attribute of the HEAD specifies the location of a meta data profile. The value of the profile attribute is a URI. User agents may use this URI in two ways:
- As a globally unique name. User agents may be able to recognize the name (without actually retrieving the profile) and perform some activity based on known conventions for that profile. For instance, search engines could provide an interface for searching through catalogs of HTML documents, where these documents all use the same profile for representing catalog entries.
- As a link. User agents may dereference the URI and perform some activity based on the actual definitions within the profile (e.g., authorize the usage of the profile within the current HTML document). This specification does not define formats for profiles.
In the case of this URI, we expect that the URI be used as a global identifier, although dereferencing the resource should always yield a description of the concept with which the URI carries.
Thanks to PURL for the URI, and to Dan Connolly for the inspiration.