Can someone explain to me the changes in fontsize in the following example?
Enclosing the fontswitches in a group did not change the behaviour.

\def\MarkMasterA{\inmargin[location=left]{\bgroup\switchtobodyfont[9pt]\red Master\egroup}}
\def\MarkMasterB{\inmargin[location=left]{\bgroup\usebodyfont[9pt]\red Master\egroup}}
\startsection[title=\MarkMasterA First title]
\input hawking
\input hawking
\startsection[title=\MarkMasterB First title]
\input hawking
\input hawking

In the first section the absolute value of 9 pt appears not to be honoured but it looks as if there is a reduction relative to the surrounding font.
In the second section the size does not change and looks even bigger than the first one above.

I am baffled and do not understand why not all fontsizes are the same absolute 9pt as requested?

Hans van der Meer