The value of this object defines the IDSL line card's timing mode as follows: internallyTimed - The IDSL line card provides an internally generated clock to all ports on the card. locallyTimed - the IDSL Line Card acquires it's clock from port #1 and distributes it to the all other ports on this card. networkTimedSlave - the IDSL Line Card aquires timing from the backplane. If the backplance clock is missing it provides internal timing to all ports on this card. networkTimedMaster - The IDSL Line Card aquires a clock according to the following protocol: a) aquire clock from port #1 and distribute it both locally and across the backplane. b) if step a) fails then aquire the clock from the backplane. c) if steps a) and b) both fail provide internal timing to all ports on this card. networkBackup - The IDSL Line Card aquires a clock for this shelf according to the following protocol: a) aquire clock from the backplane. b) if step a) fails then aquire the clock from port #1 and distribute this clock locally on this card and across the backplane. c) if steps a) and b) both fail provide internal timing to all ports on this card.