The rules that use the category "<controller>" are:
<roger> <unit_call_sign-gapsout_null-gapsin_null> <controller>
<unit_call_sign-gapsout_null-gapsin_null> <controller> <roger>
<unit_call_sign-gapsout_null-gapsin_null> <roger> <controller>
<radio_contact_verb> <controller>
<radio_contact_verb> <controller> on <frequency_code>
<radio_contact_verb> <controller> on <frequency_code> prior to <point_name>
<roger> <unit_call_sign-gapsout_null-gapsin_null> <controller>
<unit_call_sign-gapsout_null-gapsin_null> <controller>
<unit_call_sign-gapsout_null-gapsin_null> <controller> <roger>
<unit_call_sign-gapsout_null-gapsin_null> <roger> <controller>