Finding names of context menus

I'm trying to add extra menu items in an Acrobat Pro C++ plugin, but I need the strings for the menu names to use in the AVAppRegisterForContextMenuAddition function call.

The documentation only lists "Page" and "Select" and I can add to those menus OK. But I would like to add items to the context menus for right-click on an external link and an internal link. Screen captures of the popup menus are attached.

Does anyone know how to find the names of these context menus to use for the "menuName" parameter in the Register call? Thanks in advance for any input, the help is much appreciated.