The rules that use the category "<airspace_entry_mod>" are:

<airspace_clearance-recursive>

<clearance_verb> <airspace_entry_mod>

<clearance_verb> <airspace_entry_mod> <location_mod>

<airspace_clearance>

<clearance_verb> <airspace_entry_mod>

<clearance_verb> <airspace_entry_mod> <location_mod>