The category "<unit-pl>" can be expressed as follows:
<det-not_indef-pl> <unit_nom-not_det-pl>
<det-not_other-not_indef-pl> <call_sign_prefix> units
<det-not_other-not_indef-pl> <call_sign_prefix> units <except> <unit-not_except>
<full_unit_call_sign> and <full_unit_call_sign>
<unit_nom-pl>