[NTG-context] Page number in the middle of the margin

Dear all, as said by the title of the e-mail, I try to put the page number in the middle (both vertically and horizontally) of the margin. I tried a custom command like \def\mypagenumber#1{% \vfill #1 \vfill } \setuppagenumbering{location=margin,command=\mypagenumber} but, unfortunately, I got an error message on the \vfill. Is there a direct way to place my page number ? Regards, -- Flavien. ---------------------------- "Quantum objects are completely crazy but, at least, they are all crazy in the same way." R.P. Feynman.