For those interested NATS does not categorise infringements separately to other incidents. Any incident that results in a loss of Separation is investigated as is required by SRG. The report is passed to SRG. The Safety Significance Event scheme(SSEscheme) is a NATS way of categorising how serious the loss of separation actually was.
The SSE scheme is based around what resolved the incident and how close the aircraft came to each other. The categories go from 4 (the lowest) to 1 (good luck kept them apart).
If you are intersted get a visit to a centre. During your visit (if its LTCC) you will see example of infringements and the SSE scheme would be explained if you ask
