This attribute indicates the type of DE to CLP mapping that is
performed in the Frame Relay to ATM direction.
A value of preserve indicates that the DE field in a Q.922 core
frame is copied to the ATM CLP field of every cell containing the
information of that frame.
A value of always0 indicates that the CLP field of every generated
ATM cell is always 0.
A value of always1 indicates that the CLP field of every generated
ATM cell is always1.