The category "<unit_n>" can be expressed as follows:

<unit_n>

<aircraft-not_creatable>

<atf-not_creatable>

<atf_noun> <base_of_fire_phrase>

<base_of_fire_phrase>

<battalion-not_creatable>

<company-not_creatable>

<company_noun> <base_of_fire_phrase>

<flight-not_creatable>

<flight_noun> <base_of_fire_phrase>

<force> <force_word>

<landing_force-not_creatable>

<landing_force_noun> <base_of_fire_phrase>

<platoon-not_creatable>

<platoon_noun> <base_of_fire_phrase>

<section-not_creatable>

<section_noun> <base_of_fire_phrase>

<squad-not_creatable>

<squad_noun> <base_of_fire_phrase>

<team-not_creatable>

<team_noun> <base_of_fire_phrase>

<vehicle-not_creatable>

units