Constant HOLD_LAG 

const HOLD_LAG: u64 = _; // 24u64

A lone anchor every consumer holds is not marked over while the newest frame they were all sent runs more than HOLD_LAG frames ahead of the newest they all hold, as when a consumer’s link goes dark: a consumer reporting its loss once it is back is predicted past only from an anchor it holds. Past HOLD_MAX frames it is marked over all the same, a consumer that far behind taking a key frame.