I have condensed it into a single document. The footer has in the right side the page numbering and at the left the "section". Both only start at the second page, which is good. I was wondering if the "section" could have the "title" in front of it. The title always stays the same, and the section changes.
Many Thanks
Jeroen

\setuppapersize[A4,portrait]
               [A4,portrait]
\setuplayout[backspace=20mm,
             width=175mm,
             topspace=20mm,
             header=0mm,
             footer=2mm,
             height=263mm,
             bottomheight=1mm,
             footerdistance=10mm]
\usetypescript[pagella]
\setupbodyfont[pagella,12pt]
\setupcolors[state=start]
\setupfootertexts[section][]
\setupfooter[alternative=,style=\bf\em]
\setuppagenumbering[alternative=,location={footer,right},style=\bf\em]
\setcounter[userpage][0]
\setupcombinedlist[content][level=1]
\setupexternalfigures[directory={images}]
\startdocument[
  metadata:title={MkIV Context Notes},
  metadata:subtitle={},
  metadata:subject={MkIV Context},
  affiliation=Context]
\starttext
\startfrontmatter
\title{MkIV \CONTEXT\ Notes.}
\startcolumns[n=2]
\input zapf
\stopcolumns
\vfill
\placecontent
\stopfrontmatter
\startbodymatter
\section{Introduction}
\dorecurse{5}{\input knuth}
\section{Closure}
\dorecurse{5}{\input bryson}
\stopbodymatter
\startappendices
\setupcombinedlist[content][level=1]
\section{Appendix A}
\dorecurse{5}{\input tufte}
\stopappendices
\stoptext

Op zo 29 sep. 2019 om 21:36 schreef Wolfgang Schuster <wolfgang.schuster.lists@gmail.com>:
Jeroen schrieb am 29.09.2019 um 20:36:
> This is the main file.
Neither minimal nor complete and \stopdocument is also missing.
> \environment mkivcnotesenv
> \startdocument
>  [metadata:subject={MkIV Context},
>    affiliation=Context]
> \starttext
> \startfrontmatter
> \input{frontpage.tex}
> \stopfrontmatter
> \startbodymatter
> \section{Introduction}
> \dorecurse{10}{input knuth}
> \stopbodymatter
> \startappendices
> %\input{a1.tex}
> \stopappendices
> \stoptext

Are you looking for something like this (I need more information for a
better answer):

\definetext [sectionfooter] [footer] [section]
%\definetext [sectionfooter] [footer] [text] [section] []

\setupfootertexts [I'm a footer text!] [pagenumber]

\setuppagenumbering
   [location=,
    style=bolditalic]

\setuphead
   [section]
   [page=yes, % needed for the footer setting
    footer=sectionfooter]

\starttext

\section{Introduction}

\dorecurse{10}{\input knuth}

\stoptext

Wolfgang