The category "<contact_type>" can be expressed as follows:
<contact_type-point_id_type_none> <air_formation_mod>
<contact_type_nom-point_id_type_none> <aircraft_activity> <contact_type-point_id_type_none-simple>
<contact_type_nom-point_id_type_none-pl>
<contact_type_nom-point_id_type_none-sing>
<det> <contact_type_nom-point_id_type_none>
<digit-not_zero-pl> <contact_type_nom-pl>
<digit-not_zero-pl> <contact_type_nom-point_id_type_none-pl>
<digit-not_zero-sing> <contact_type_nom-point_id_type_none-sing>
<digit-not_zero-sing> <contact_type_nom-sing>
<group_contact_id> <contact_type-point_id_type_none-simple>