The egress generated VPI value of this ATM PW. The
entry is valid for PW type of atmCellNto1Vcc(9),
atmCellNto1Vpc(10), atmCell1to1Vcc(12), or
atmCell1to1Vpc(13). In other types, the value will be the
equivalent of 0xFFFF. Value MAY be changed when the
PW is defined as not active