[NTG-context] Custom enumeration

Dear ConTeXters, A newbie question: I am trying to set up a custom enumeration for exercises in a syllabus. The numbering of these exercises should reflect both part and chapter information, but \defineenumeration does not allow me to write my own custom command for this (unlike \setuphead). Am I missing something, or is there another solution? Thanks in advance for any help. -- Bela Mulder Group Leader Theory of Biomolecular matter FOM Institute AMOLF Science Park 104, 1098XG Amsterdam, THE NETHERLANDS Tel: + 31 20 7547100 FAX: + 31 20 7547290 web: http://www.amolf.nl/research/theory_of_biomolecular_matter/