"Activating with .mso"
*** de trace enter: after
*** trace exit: after
Here, the tracing is activated within the document, not by a command line option. As tracing was not active when macro before was defined, no call of this macro is protocolled; on the other hand, the macro after is fully protocolled.
The trace macros are kept in the file trace.tmac located in the "tmac directory"; see groff_tmac(5) for details.