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

<unit_nom-sing>

<unit_n-sing> <location_prep> <engagement_loc>

<unit_nom>

<unit_n> <location_prep> <engagement_loc>

<location_mod>

<location_prep> <point_loc>

<unit_nom-not_det-sing>

<unit_n-not_det-sing> <location_prep> <engagement_loc>

<unit_nom-not_det-pl>

<unit_n-not_det-pl> <location_prep> <engagement_loc>