This read-write value sets the physical number identifying a FlexE physical interface within its group, ranging from 0 or 1 to 254. An admin configures this so the interface's physical number matches what the remote end expects, since a discrepancy generates the module's hh3cFlexEPhyNumberMismatch notification. For example, if an admin sets this to 2 on the local interface but the remote peer reports its own physical number as 3, the mismatch trap fires until the numbers are aligned.