Virtual concatenation: a clarification on sequence numbers

[<gopi@india.tejasnetworks.com>]

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hi..

I was going through the thread
        http://ops.ietf.org/lists/ccamp/ccamp.2001/threads.html#00295
        subject: "concatenation extensions in sonet/sdh"

I needed a small clarification on virtual concatenation sequencing

Sequence number is sent by the transmitter and receiver checks for
the sequence number to perform interleaving.

  IS this sequence number "Provisioned"(on both terminating equipments) ?
   OR
  Is it automatically assigned by the transmitting equipment in some
  sequence and the receiver synchronizes with the transmitters sequence number?


I read the following relevant standards on virtual concatenation, but couldn't
clearly understand how the receiver knows the sequencing of the
individual links.
+ T1X1.5/2001-062(Synchronous Optical Network (SONET) - Basic
    Description including Multiplex Structure, Rates and Formats,
    put up on ftp.t1.org/..../1X150620.DOC)
+ G.707, G.783(virtual concatenation)
+ G.7042(LCAS)

Thanx in advance
Gopi