Section 8.5 - Alternate Hierarchies does not represent the notion of metainformation well. Suggest we use "Tagging" as a title.

A server MAY present Tags that reference additional information about each OBIX object. If these Tags are part of a formal semantic model, i.e., Haystack, BIM, etc., then the tags will be identified by reference to its source semantic model. The identifier for such tags, along with the URI for the semantic model it represents, are declared in the lobby.
[example]
Insert after 1013.
OBIX Clients SHALL ignore information that they do not understand. In particular, a conformant client that is presented with Tags that is does not understand MUST ignore those tags. No OBIX server may require understanding of these tags for interoperation.