This read-create INTEGER, set to internal(1) or external(2), identifies the Primary Reference Source this clock source traces to, with internal meaning an onboard local oscillator and external covering all other cases, and per the description this value serves as a further NCDP tiebreaker (the truncated text indicates ordering logic follows). An admin sets this to accurately reflect whether a given source ultimately derives from the device's own oscillator or an outside reference, which matters for NCDP's tiebreaking among sources tied on priority and stratum. A source configured as external(2) when it's actually just the local oscillator would mislead NCDP's tiebreaking and should be corrected by the admin.