The items in this menu are used to change which entry is the default entry and which entries are active (see the section called The "Entry" in Chapter 1). At the bottom of the menu there is a toggle button for each entry which controls whether the entry is active or not.
Here is a description of the other menu items:
Set the name of an entry chosen from a sub-menu. The name of the entry is used as the name of the file when the entry is saved.
Set the default entry by choosing one of the entries from the sub-menu. (See the section called The Default Entry in Chapter 1).
Remove an entry from ACT by choosing one of the entries from the sub-menu. The original file that this entry came from (if any) will not be removed.
Remove the entries that are currently active. (See the section called The Active Entries in Chapter 1).
Choosing this menu item will deactivate all entries. (See the section called The Active Entries in Chapter 1.)