Using KDE’s DigiKam on macOS I noticed that many interface elements (such as context menu items or tool selectors, see image below) have a letter in their name underlined, which appears (at least to me) to indicate that the letter can be used as a shortcut to activate a given menu element.

However this does not appear to be the case, as those menu items and other commands are not activated neither by typing the letters by themselves nor by using them in any combination with command, alt or control.

How are these underlined letters supposed to be used? Is there a standard way, or is it something specific to DigiKam (or even something that works on its Linux version and was not implemented on macOS)? I have only seen a few apps on macOS that use underlined letters to suggest keyboard shorcuts, and in those other instances I don’t remember using them.

I realize this question might be off-topic here if the answer is something just related to DigiKam, but since its developers don’t seem to mention these underlined letters in their documentation I figured that there might indeed be an “obviuos” was to use them which would be defined by the operating system…