Whoops! I should have made myself more clear!
Indeed, 50 nm separation standards are used when aircraft have ADS-C (contract), as opposed to ADS-B (broadcast). When the rollout of ADS-B is complete - we should have the ability to use a lateral separation of just 5 NM between two ADS-B equipped aircraft.
This is possible, because unlike ADS-C, where postition reports are made either every 30 minutes (or another time interval set by the controller, or over a waypoint, an ADS-B unit transmits it's position every 1/2(?) a second.
There, hope I haven't made it more confusing again
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