# Can I assign “U” for “undo”?

I come from a very different CAD background with years of muscle memory with other tools that I would like to use with Blender.
Right now, I would like to associate the key U with "undo." However, if I assign it in User Preferences, and re-assign "Make Single User" (in "NLA Editor" group) to a different combination, I still get the "Make Single User" menu when pressing U.

Is there a way to re-map "undo" to U? I've successfully mapped ShiftZ and CtrlZ to zoom-out and zoom-in, respectively, for what it's worth. (note: the CtrlZ to zoom-in, which I've grown accustomed to, is the particular qualifier why I'd like another key to "undo".)

I'm currently using Blender 2.75a under Arch Linux.

There are U shortcuts in the 3D view (both in object mode and edit mode) which call the call_menu() operator. This is different from the NLA editor, which just runs nla.make_single_user() directly when called since it has no options.