/etc/X11/Xsession.d/80kubuntu-xmodmap is in kubuntu-default-settings 1:12.04ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12  | # Set custom keycodes
#
# This file is sourced by Xsession(5), not executed.
# The "|| true" is to ensure that the Xsession script does not terminate on error
USRMODMAP="$HOME/.Xmodmap"
if [ -x /usr/bin/xmodmap ]; then
        if [ -f "$USRMODMAP" ]; then
                /usr/bin/xmodmap "$USRMODMAP" || true
        fi
fi
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