The underneath example works with \def\myHeader{\iftuut chapter\else high\fi} How do you make it work with\def\myHeader{\doifmodelse{a}{chapter}{high}} ? ( without resorting to \doifmodeelse{a}{\tuuttrue}{\tuutfalse} ) \showframe \newif\iftuut %\tuuttrue \tuutfalse \setuppagenumbering[location=footer] \setupheadertexts[\doifoddpageelse{right page}{left page}] \definetext[chapter][header][chapter page] \def\myHeader{\doifmodelse{a}{chapter}{high}} %\def\myHeader{\iftuut chapter\else high\fi} \setuphead [chapter] % [header=chapter] % [header=high] [header=\myHeader] \starttext \dorecurse{2}{\chapter{Chapter #1}\dorecurse{20}{\input knuth\par}} \stoptext --- ! Undefined control sequence. \myHeader ->\doifmodelse {a}{chapter}{high} \doifvaluesomething ...inga {\csname #1\endcsname }\ifx \!!stringa \empty \e... <argument> ...ething {\??ko \v!chapter \c!header } {\setuplayouttext [\v!hea... \firstoftwoarguments #1#2->#1 <argument> ...BB {\v!chapter }\v!header \c!header \dohandlepagebreakBB {\v!c... \firstofoneargument #1->#1 ... l.23 ...apter #1}\dorecurse{20}{\input knuth\par}} --- Alan