There are two general types of bargaining units. The
first is a comprehensive bargaining unit which is also
known as vertical, industrial, or wall-to-wall. This
type of bargaining unit usually includes all "production
and maintenance employees" regardless of their
skill or classification. The second type is a craft
unit which is also known as inclusive or horizontal.
This type of bargaining unit may be defined very specifically
(e.g., nurses, flight attendants, engineers).