The category "<establish_base_of_fire_command-gapsout_null-gapsin_null>" can be expressed as follows:

<establish_base_of_fire_command-gapsout_null-gapsin_null>

<set_up_verb> <base_of_fire_phrase>

<set_up_verb> <base_of_fire_phrase> <engagement_loc_mod-gapsout_null-gapsin_null>

<set_up_verb> <base_of_fire_phrase> <engagement_loc_mod-gapsout_null-gapsin_null> <open_fire_verb> <on_order>

<set_up_verb> <base_of_fire_phrase> <engagement_loc_mod-gapsout_null-gapsin_null> targeting <on_prep> <enemy_loc-gapsout_null-gapsin_null>