Dear John,

I was playing with some code from the "details" manual. My intention was 
to make "thumbholes" i.e. a coloured mark with the chapter number on it 
at the edge of the page at each starting chapter. The idea is then to 
cut the pages before that mark ... Though there is certain progress I am 
unable to use the \headnumber[chapter] in a calculation to move the mark 
down the edge for each chapter until arrived at the bottom and then 
restart at the top ... (This is a wish of a bookbinder for preparing a 
manual ...)

But I was able to make your "problem" work with the same approach. 
Please refer to the attached file "bleedingpagenumber.tex". Though it 
does surely not win a price for beauty, it works. You will have to play 
with the different x and y, width and height components to move the 
pagenumber to the desired place. ...

Kind regards Willi

John Culleton wrote:
> I want to place the page number vertically centered in the 
> outer margin, with some prettyprinting. Does one do this 
> with the \setpagenumber command, the \inmargin command, or 
> some combination thereof?
> 
> I can figure out how to do it in plain TeX but I hate to 
> revert to plain just for this feature.