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

<full_unit_call_sign>

<unit_call_sign>

<unit_name_mod>

<name_adj> <unit_call_sign>

<name_operation>

<naming_verb> <unit> <unit_call_sign>

<naming_verb> <unit> as <unit_call_sign>

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

<naming_verb> it <unit_call_sign>

<unit_call_sign_list>

<unit_call_sign>

<unit_call_sign> <unit_call_sign_list>