To insert in my international (USA) keyboard other symbols, instead of using the method with xmodemap, I want to try a new (at least for me) approach.

Generally in Linux are present a few key combinations which must be written somewhere to become active.

An example is (try it):

AltGr (that is the Alt key on the right) + Shift + "q" -> Ω
.

Is there someone who knows in which file this key combination is defined?

If I succeed in inserting new symbols, I 'll let you know...

Look at my homesite:
http://www.gablin.fr.fm
Be sure to block pop-ups (those are forced on me...)
When there, click on Linux and the English flag on top of the screen.

Yves.

Your homesite is very "jolie" (I bookmarked it).
I will read it carefully... but it wasn't the question.
Au revoir.

It depends... If you want to get a particular X symbol for a particular keys combination, then my site may help you. It is not the all-done answer, but it may point out things you'll need.
However, if you're happy with the current mapping, there are two options:

1) In /etc/XF86Config-4, add a keyboard option, so that one of your keys (usually right Win key) is the X "Compose" key. This can be done with xf86cfg or xf86config command. Then find out where the valid "Compose"-itions are defined, and change the file so that Compose+key1+key2=Omega for example.

2) Else you may install a key listener (don't remember the name) program, and instruct it to send the Omega event on alt-whatever.

Good luck.

Yves.
BTW: Thanks for the comment about my site.

I can't use the "Compose" key because I don't know what key use ( my keyboard has no Win keys).

A key listener seems a little too cumbersome solution...

If I knew what to search for in the configuration files, I could use grep all over the file system (it will take less than waiting an answer from forums...).

Thinking of it, the Mandrake producers (I use mdk 10), must use the right Alt key as a "Compose" key, if not I sholdn't have at disposal all that key combinations (mainly Unicode symbols)...