Hi Marco, It's a bug, I think. The keys that control this are way and prefixsegments: \setupformulas[way=bychapter, prefixsegments=chapter] way=bychapter means 'resume numbering at each chapter' prefixsegments=chapter means 'precede each formula number with the chapter number': chapter.formula Right now, as soon as I set 'prefixsegments' to 'section' or 'chapter' or a number, the prefix segments disappear. Ditto when I set 'way' to anything. This suggests that it is a bug. Is it indeed, Hans? I've attached a test file for you. You can use \setupformulas[prefixsegments=] to solve your problem if you never want prefixes; that also specifies the correct behaviour once the bug is fixed. Cheers, Sietse