This attribute specifies the type of CLP to DE mapping to be
performed in the ATM to Frame Relay direction.
When preserve is selected, the DE field of the Q.922 core frame is
set when one or more ATM cells belonging to the frame has its CLP
field set, or when the DE field of the FR-SSCS PDU is set.
When transparent is selected, the DE field of the Q.922 core frame
copies directly from the DE field of the FR-SSCS PDU.