itermset — A set of index terms in the meta-information of a document
When IndexTerms use the Zone
attribute to point to index ranges, it may be handy to hoist them
out of the flow and put them in the document meta-information.
The ITermSet element, which occurs in the DocBook containers
for meta-information, is one place to put them.  ITermSet is
simply a wrapper around a group of IndexTerms.
Suppressed.
Although more than one ITermSet may appear in the
meta-information for a document, neither a relationship nor a specific
facility for constructing a relationship is defined.
These elements contain itermset: biblioentry, bibliomixed, bibliomset, biblioset, info (db.info), info (db.titleforbidden.info), info (db.titleonly.info), info (db.titleonlyreq.info), info (db.titlereq.info).