jbf schrieb am 03.06.2020 um 01:21:
>
> Thanks Wolfgang. Clearly that fixes the problem. I also came up with 
> another solution which avoids the need to define a MyChapterCommand, 
> by first setting up the normal chapter as:
>
> \setuphead
>   [chapter]
> [header=empty,alternative=middle,style=bold,numbercommand=\groupedcommand{}{\blank[2cm]},after={\blank[3cm]}]
>
> and then setting up a mychapter as:
>
> \definehead[mychapter][chapter]
>
> \setuphead[mychapter][header=empty,alternative=middle,style=bold,numbercommand=\groupedcommand{}{\blank[2cm]},after={\blank[.5cm]}]
>
> That gives me the result I am after as well as maintaining the style 
> of the standard chapter head.
>

You can add a check for odd/even chapter numbers and use only a single 
command.

\startsetups[chapter:after]
   \ifodd\namedheadnumber{chapter}
     \blank[4cm]
   \else
     \blank[1cm]
   \fi
\stopsetups

\setuphead
   [chapter]
   [after=\directsetup{chapter:after}]

% \setuphead
%   [title]
%   [after={\blank[...]}]

\starttext

\dorecurse{10}
   {\chapter{Chapter #1}
    \input knuth}

\stoptext

Wolfgang