The category "<air_command_prefix-roger>" can be expressed as follows:

<air_command_prefix-roger>

<controller> <roger>

<roger>

<roger> <controller>

<roger> <unit_call_sign-gapsout_null-gapsin_null>

<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>

<unit_call_sign-gapsout_null-gapsin_null> <roger> <controller>