FRMCMP changes FMB file

Hi, can anybody explain what happens: when I compile a form with command

c:\Oracle\Middleware\FRHome\BIN\ frmcmp userid=<...> module=<name> batch=YES module_type=FORM compile_all=YES window_state=minimize

all works OK, but my source FMB file becomes reduced in size (very much, almost twice)!

Forms [64 Bit] Version 11.1.2.2.0 (Production)

Happens with all modules, in all environments.

"Reduced" forms seem to be quite correct.

Thanks in advance,

G.R.