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

<open_fire_command>

<open_fire_command_1> <on_order>

<establish_base_of_fire_command>

<set_up_verb> <base_of_fire_phrase> <location_prep> <engagement_loc> <open_fire_verb> <on_order>

<control_method>

<on_order>