This read-write value sets the percentage of time the port's transmit scheduler spends refilling the queue using the priority-order sequence 0, 1, 2, 3, strictly favoring priority 0 first, as one of several configurable refill patterns. An admin tunes this alongside the sibling Priority1, Priority2, and Priority3 percentage objects to implement a weighted round-robin-like scheduling scheme across the four priority classes rather than strict priority queuing. For example, setting lportXmitRefillPriority0Percentage to 40, with the others making up the remaining 60%, means 40% of refill cycles favor draining priority 0 first, giving that class a strong but not absolute precedence over the others.