Xorg and composite UNICODE characters

[Matej Kosik <5764c029b688c1c0d24a2e97cd764f@gmail.com>]

Hi,

I am trying to create a keyboard layout variant, that would enable me to type some of the IPA characters I need.

E.g., if I want to access

	ɔ

via

	Alt+o

I change

	key <AD09> { [ o, O, NoSymbol, NoSymbol ] };

to

	key <AD09> { [ o, O, U0254, NoSymbol ] };

in the corresponding /usr/share/X11/xkb/symbols/* file.
This works because encoding of "ɔ" in UNICODE is 0x0254.
(according to http://www.phon.ucl.ac.uk/home/wells/ipa-unicode.htm)

So far, so good.

Then I tried to make:

	ɔ̃

accessible via

	Alt+Shift+o

No I am not sure how can I do that.

Neither:

	key <AD09> { [ o, O, U0254, U02540303 ] };

nor

	key <AD09> { [ o, O, U0254, U03030254 ] };

works.

What is the right way to do it (i.e. how to map some existing key to ɔ̃ ?)

Thanks in advance for any hints.