This attribute specifies the type of FECN to EFCI mapping that is
performed in the Frame Relay to ATM direction.
When preserve is selected, the FECN field in the Q.922 Core frame
is mapped directly to the ATM EFCI field of every cell generated by
the AAL5 segmentation process.
When always0 is selected, the EFCI field in every ATM cell
generated is set to 0.