Keypad plus and minus names in ~/.XCompose

Question

I use XIM under Debian Linux with Gnome 2. Many compose sequences are already defined in the system, including the one for ± sign:

palec@Palec:~$ grep PLUS-MINUS /usr/share/X11/locale/en_US.UTF-8/Compose
<Multi_key> <plus> <minus>          : "±"   plusminus # PLUS-MINUS SIGN

This does not work with numpad of my Lenovo G550’s keyboard.

I noticed that numbers on numpad require KP_ prefix to be matched, so I tried adding copy of the original rule with keys changed to KP_plus and KP_minus to my ~/.XCompose, where I already have other rules I use in addition to those from the system Compose file. No luck though.

I did not manage to find any useful doc for XIM nor ~/.XCompose. Is there any? Most of information on XIM and compose sequences I got from forums I found by googling. How to get the name of a key for use in ~/.XCompose? Particularly, what are they for numpad + and -?

I do not insist on XIM, but I want to be able to configure custom compose sequences. If there is another, preferably better documented solution, I’d like to hear about it.

Answer 1

1. How to get the name of a key: Use the command xev and press the keys of interest. The name is shown as last word in the parenthesis.
2. Particularly, what are the names for numpad + and −: xev tells me, that they are KP_Add and KP_Subtract.