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

<attach_unit_operation>

attach <unit> to <unit>

attach <unit> under <unit>

<cancel_operation>

<cancel_verb> <unit>

<telegraphic_command>

<telegraphic_unit_command> for <unit>

<unit> <telegraphic_unit_command>

<development_command>

<unit> <debug_command>

<name_operation>

<naming_verb> <unit> <unit_call_sign>

<naming_verb> <unit> as <unit_call_sign>

<naming_verb> <unit> with new name <unit_call_sign>

<control_measure_clause>

<unit> <reach_verb> <engagement_loc>