CUA recommends that applications are written with both mouse and keyboard use in mind. To facilitate this, menus should be accessible through accelerators. Accelerators allow the user to access menus by depressing combinations of keys, usually Alt plus some letter. They also permit selection of a choice from a menu by a single letter.
This does not necessarily work in applications that use those key combinations themselves. If, for instance, a menu provides "File" in a menu, then the capital F cannot be used within the application for a function like "Find". In those cases either the key combinations in the application have to be modified (often possible in a profile) or the mouse or function keys have to be used. Please note that uppercase and lowercase characters may be treated differently. This is one of the reasons why CUA demands that applications respect a number of definitions, for example F1=HELP.