Hello,
I would like that on the pages with the title of the chapter the header is empty.

Fabrice

\setupheadertexts[{\getmarking[section]}][pagenumber]
                              [{\getmarking[chapter]}][pagenumber]

\setuppagenumbering[alternative=,location=]
\starttext
\placelist[chapter,section][alternative=c]
\startchapter[title={First chapter}]
\startsection[title={First section}]
  \dorecurse{5}{\input knuth} 
\stopsection
\stopchapter
\startchapter[title={Second chapter}]
\startsection[title={Second section}]
  \dorecurse{5}{\input knuth} 
\stopsection
\stopchapter
\stoptext