Specifies the payload carried by the SONET/SDH Path.
The payload specification corresponds to C2 (Signal Label)
overhead byte in SONET/SDH Path Overhead:
unequipped(1) : Path is not provisioned to carry any payload.
unspecified(2) : Path is carrying an unspecifed payload.
ds3(3) : Path is carrying a DS3 path as payload.
vt15vc11(4) : Path is carrying SONET-VT1.5/SDH-VC11 payload.
vt2vc12(5) : Path is carrying SONET-VT2/SDH-VC12 as payload.
atmCell(6) : Path is carrying ATM Cells as payload.
hdlcFr(7) : Path is carrying Frame Relay (HDLC) payload.
e3(8) : Path is carrying an E3 path as payload.
vtStructured(9) : Path is carrying VTGs/TUG3s/TUG2s which may
each carry a different payload.
A write operation on this object will result in update to
C2 overhead byte in the Path Overhead.