[NTG-context] cross references to chapters in a book

Dear wizards of ConTeXt, In the final stage of completing a book project, I was wondering how to automatize cross references to chapters. I’ve already figured out how to refer to pages (using “\at[REFERENCE]”), but how is this done with chapters? I’m apparently too simple-minded to understand the manual (and I don’t understand the differences between \reference, \textreference, \in, \about). Robert