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

<move_mod-not_compass_direction>

<to_prep> <point_loc> on <line_loc>

from <engagement_loc> <to_prep> <engagement_loc>

<compass_direction>

<to_prep> the <cardinal_direction>

<suppress_by_fire_command>

<movement_verb> <to_prep> <engagement_loc> and <suppress_by_fire_verb> <by_fire_phrase>

<movement_verb> <to_prep> <engagement_loc> and <suppress_by_fire_verb> <enemy_loc> <by_fire_phrase>

<movement_command-not_with_compass_direction>

<report_verb> <to_prep> <engagement_loc>

<report_verb> <to_prep> <point_loc> on <line_loc>

<attack_by_fire_command>

<movement_verb> <to_prep> <engagement_loc> and <engage_verb> <enemy_loc> <by_fire_phrase>

<movement_verb> <to_prep> <engagement_loc> and <plain_attack_by_fire_verb> <by_fire_phrase>

<movement_verb> <to_prep> <engagement_loc> and <plain_attack_by_fire_verb> <enemy_loc> <by_fire_phrase>

<objective_mod>

<to_prep> <engagement_loc>

<movement_command>

<report_verb> <to_prep> <engagement_loc>

<report_verb> <to_prep> <point_loc> on <line_loc>

<bearing_mod>

<bearing_adj> <to_prep> <bearing_spec>

<bearing_adj> <to_prep> <point_loc>