This attribute indicates the type of CLP to DE mapping that is
performed in the ATM to Frame Relay direction.
A value of preserve indicates that 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.
A value of transparent indicates that the DE field of the Q.922 core
frame copies directly from the DE field of the FR-SSCS PDU.