Why all strings... ? (gettext question)

[Sever P A <gnu sever gmail com>]

Hello,

All this weekend trying unsuccesfully to understand why the command:

xgettext -a -o my-strings --omit-header --from-code=utf-8 *.cc  (that
could be seen without --from-code option in the chapter 24 of Gtkmm
tutorial)

gets all strings, including those which are filenames, initialisation
strings, etc... ?

I believed that only the strings inside gettext() would be extracted...

Something wrong ?

S.