boundaries. @xref{Basic Completion}, for the precise expected semantics
of completion boundaries.
+@cindex completion metadata
@item metadata
This specifies a request for information about the state of the
current completion. The return value should have the form
may return in response to a @code{metadata} flag argument:
@table @code
+@cindex @code{category}, in completion
+@cindex completion category
@item category
The value should be a symbol describing what kind of text the
completion function is trying to complete. If the symbol matches one