Modmap settings to combine US layout and German umlauts

The following .Xmodmap file should work to modify an US layout to give German umlauts when the corresponding keys are pressed together with the right Alt key:

! Xorg 8.10 has different keycode for Right-Alt
! keycode 113 = Mode_switch
keycode 108 = Mode_switch
keycode 20 = minus underscore ssharp
keycode 34 = bracketleft braceleft udiaeresis Udiaeresis
keycode 47 = semicolon colon odiaeresis Odiaeresis
keycode 48 = apostrophe quotedbl adiaeresis Adiaeresis
keycode 26 = e E EuroSign

This should work for Xorg 8.10 (e.g Ubuntu Intrepid Ibex, previously the keycode for the right Alt key was 113). This came as a bit of a surprise, as my left arrow key and the umlauts didn't work anymore after upgrading to Ubuntu Intrepid Ibex.

The keycodes for keys can easily be found using xev.