msgsub — A subcomponent of a message in a message set
A MsgSub represents some subpart of a message.  Different
MsgSubs might arise in different contexts.
May be formatted inline or as a displayed block, depending on context. Sometimes suppressed.
On the whole, the semantics of MsgSet
are not clearly defined.
The following elements occur in msgsub: info (db.titleforbidden.info), info (db.titleonly.info), msgtext, title, titleabbrev.