the shortcut alt (⌥) + N is used on a Mac for entering the character ñ, which is often used in Spanish and any Spanish-based orthography. In ELAN, this shortcut is assigned to something else, so that entering ñ in ELAN becomes very difficult.
There are only a few default keyboard shortcuts consisting of Alt+character left, most have been replaced. Alt+N has a long history as the shortcut for creating a new annotation. On my test Mac OS 10.11 it is still possible to use the Mac’s Alt+Letter combination to enter a diacritic first, once a text edit field is visible for an annotation.
It is possible to change the default ELAN keyboard shortcuts for most actions via Edit-> Preferences->Edit Shortcuts… so that any shortcut that is in the way of a system defined shortcut can be changed or removed.
-Han