The rules that use the vocabulary item "at" are:

<normalize_pvd_operation>

center terrain at standard scale

<location_prep>

at

<temporal_control_method>

<sp> at <time_point>

at <time_point>

<bearing_mod>

pointing at <point_loc>

<create_operation>

<point_name> is at <coordinates>

<ship_speed_command>

proceed at <ship_speed>

<ship_speed_mod>

at <ship_speed>