Otherwise the search is limited to the current buffer.
Return position of entry if CROSSREF-KEY is found or nil otherwise.
If CROSSREF-KEY is in the same buffer like current entry but before it
-an error is signaled. If NOERRER is non-nil this error is suppressed.
+an error is signaled. If NOERROR is non-nil this error is suppressed.
Optional arg PNT is the position of the referencing entry. It defaults
to position of point. If optional arg SPLIT is non-nil, split window
so that both the referencing and the crossrefed entry are displayed.