Identifies the target node's line controller for the service circuit
 over which the operation is to take place.  The possibilities are
 as follows.

                BNA  CEC  DA   DL   DLV  DMB
                DMC  DMF  DMP  DMR  DMV  DP
                DQ   DSB  DSF  DSW  DTE  DU
                DUP  DV   DW4  DZ   ELA  ERA
                ETA  EWA  FPA  FZA  ISA  KDP
                KDZ  KL   MFA  MNA  MXE  PCL
                QNA  SVA  TRA  TRE  TRP  UNA
                VLA

 Only the synchronous port on the DMF service device may be used.