ISO_Level3_Shift vs. Mode_Switch
leoboiko at gmail.com
Wed Feb 28 12:25:51 PST 2007
Hi. I’m sorry if this is the wrong list, or if these questions have
been asked before, but the more I google about it the more confused I
Recently I’ve been playing with customizing ~/.xmodmap and ~/.XCompose
in order to use the AltGr and Compose keys. I had moderate success;
now I can use all sorts of typographical punctuation, macroned vowels,
cute Unicode symbols etc.
However, I’m confused about AltGr’s two “personalities” under X,
Mode_switch and ISO_Level3_Shift:
* My friend’s X server seems to be configured to use AltGr as
Mode_switch. In order to customize his AltGr mappings, he needs to
edit fields 3 and 4 of the ‘keycode’ command in ~/.xmodmap (IIRC
field 1 is just the key, 2 is Shift, 3 is Mode_switch, 4 is
Mode_switch + shift).
* My X came with AltGr mapped to ISO_Level3_Shift. To customize my
AltGr, I need to edit fields 5 and 6. As far as I can see no
physical key came mapped to Mode_switch, so fields 3 and 4 are
ignored. This makes my .xmodmap file awkward, as I have to put
placeholders on those fields. I tried changing my AltGr to
Mode_switch, but then I lost all the default X AltGr mappings (many
of which are standard in my keyboard model, Brazilian ABTN2).
What puzzles me is that we’re using exactly the same xorg version
(1:7.1.0-12 under Debian), the same keyboards (ABNT2-104 IBM Model Ms),
and the same keyboard configuration in xorg.conf.
So my question is, what’s the difference between Mode_switch and
ISO_Level3_Shift supposed to be? Why some servers use one or other? I
heard that ISO_Level3_Shift is the ‘proper’ keysym for AltGr; in that
case, what is Mode_switch good for?
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