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

<call_sign_prefix>

<any_letter> <digit>

<up_to_two_digits-sing>

<digit> <digit-sing>

<up_to_two_digits-pl>

<digit> <digit-pl>

<tens_number-complete_number>

<digit-not_zero> <digit>

<minutes>

<digit_zero_to_five> <digit>

<tens_number-pl>

<digit-not_zero> <digit>

<point_id-checkpoint>

<digit-not_zero> <digit>

<number>

<digit>

<digit> <digit>

<up_to_two_digits>

<digit> <digit>

<bearing_number-three_dig>

three <up_to_six> <digit>

<tens_number-complete_number-pl>

<digit-not_zero> <digit>

<bearing_number>

three <up_to_six> <digit>

<two_digits>

<digit> <digit>

<hundreds_number>

<digit> hundred

<digit> hundred <tens_number-not_digit_sequence>

<bearing_number-pl>

three <up_to_six> <digit>

<bearing_number-three_dig-pl>

three <up_to_six> <digit>

<up_to_four_digits>

<digit> thousand

<decimal>

point <digit>

<unit_call_sign-gapsout_null-gapsin_null>

<any_letter> <digit>

<any_letter> <digit> <any_letter>

<any_letter> <digit> <any_letter> <digit>

<any_letter> <digit> <digit>

<coordinate_digits-2>

<digit> <digit>

<number-pl>

<digit> <digit>

<coordinate_digits-3>

<digit> <digit> <digit>

<battle_position>

<battle_position_noun> <digit> <digit> <digit>

<tens_number>

<digit-not_zero> <digit>

<coordinate_digits-4>

<digit> <digit> <digit> <digit>

<loadable_item_callsign>

<soldier-sing> <digit> <digit> <digit>

pallet <digit> <digit> <digit>