EXFO FTB-8510B Guia Del Usuario página 1281

Glossary
SONET - VT Path Overhead
Z7: VT Path Growth
Bit 1 of the Z7 byte is allocated for an extended signal label. Bits 12 to 19 of
the 32 bit frame multiframe (see Z7 Structure on page 630) contain the
extended signal label.
Bit 2 of the Z7 byte is allocated for virtual concatenation. Bits 1 to 5 of the 32
bit frame multiframe (see Z7 Structure on page 630) contain the LO virtual
concatenation frame count while bits 6 to 11 contain the LO virtual
concatenation sequence indicator.
Bits 3, and 4 of the Z7 byte are unassigned and reserved for APS signaling
for protection at the lower order path level.
Bits 5 through 7 of the Z7 byte in combination with bit 8 of V5 are allocated
for RDI -V/ERDI-V signal.
Bit 8 of the Z7 byte is unassigned and reserved for a lower order path data
link.
631
SONET/SDH Application