I looked in the docs, but there is no explicit discussion on setting up parts formatting, and it's not intuitively obvious (at least to me) how to apply the procedures for, say, sections (which are formatted by default) to those for parts (which are not).
parts are formatted like any other sectioning commands. Ok, it should be mentioned somewhere that "part" has no default setup.
\setuphead[part] [style={\ss\bfc}, page=yes, number=yes, placehead=yes, align=right, before={}, after=\blank, header=empty]
For part 1, I get "Part 1..." at the top of the page, and text (beginning with the first section) begins right after it.
That makes "after=\blank" (only one empty line after the part line; I needed that because the first chapter of a part should begin on the part page).
For part 2, I get (as I was looking for) "Part 2..." on a separate page, plus a blank page that follows, and then the sample chapter.
If you are not paper restricted (my book had to fit into a fixed page frame), you normally should use "page=right" and no "before" or "after".
Just so I understand this, is this explained by some interaction between the chapter setup commands, and the parts?
Maybe. Perhaps your chapter is defined with "page=right". You didn't show us your chapter setup, and I can't find my cristal ball. Grüßlis vom Hraban! -- www.fiee.net/texnique/ www.ramm.ch/context/