xref vs. olink

I'm cross posting 
this from the docbook list...

I'm wondering which 
is more appropriate for creating cross-references when working with modular 
content: xref or olink?

 

xref has very well 
defined behavior, but causes validation errors in modules that have references 
to other modules. olink is tool chain specific, but doesn't have the validation 
problem.

 

I'm working in an 
environment where section elements are the basic building blocks of the complete 
documents. I also need to be able to publish single chapters out of a 
book.

 

We use docbook 4.5 
and have the tool chain set to prefer internal olinks.