Cross-References in a multiple file document

[Claus Hentschel]

I want to write a multiple document file where one file is used to insert
the others for printing using Insert->File (\insert).

My Question is: How can I make a cross-reference into another file? When
invoking Insert-Cross-Reference I do only see all locally defined labels
(i.e. defined in that chapter) and there is no thing to use another chapter
file as source!?

Claus