The rules that use the category "<item_n-pl>" are:

<item>

<det-pl> <item_n-pl>

<det-pl> <item_n-pl> <location_mod>

<item-not_call_sign>

<det-pl> <item_n-pl>

<det-pl> <item_n-pl> <location_mod>

<new_item>

<up_to_thirty-pl> <item_n-pl>