schema.prefix

Encoding Dublin Core Metadata in HTML [RFC2731]

   The LINK tag of HTML may be used to associate an element name prefix
   with the reference definition of the element set that it identifies.
   A sequence of META tags describing a resource is incomplete without
   one such LINK tag for each different prefix appearing in the
   sequence.  The previous example could be considered complete with the
   addition of these two LINK tags:

       <link rel     = "schema.DC"
             href    = "http://purl.org/DC/elements/1.0/">
       <link rel     = "schema.AC"
             href    = "http://metadata.net/ac/2.0/">

   In general, the association takes the form

       <link rel     = "schema.PREFIX"
             href    = "LOCATION_OF_DEFINITION">

   where, in actual descriptions, PREFIX is to be replaced by the prefix
   and LOCATION_OF_DEFINITION by the URL or URN of the defining
   document.  When embedded in the HEAD part of an HTML file, a sequence
   of LINK and META tags describes the information in the surrounding
   HTML file itself.  Here is a complete HTML file with its own embedded
   description.

[引用： 4. The LINK Tag -- [rfc2731] より]