Value of Part Sequence Number Parameter in TC(13,9)

[pasetti]

According to clause 8.13.2.4 (TC[13,9] uplink the first part), the command (13,9) carries the "Part Sequence Number" as one of its parameter. I assume that the value of this parameter must be 1 but this does not seem to be stated in the PUS. Or should I perhaps assume that a value of this parameter different from 1 counts as a "discontinuity" in the sense of clause 6.13.4.3.2f?

For reference, the full text of clause 6.13.4.3.2f is: "The receiving entity of the large packet uplink subservice shall abort the uplink operation when a discontinuity is detected in the uplink reception sequence".