Apparently level 6 just means that English is your native language and you're pretty much guarenteed to pass it as SRG inspectors are allowed to assess you with no formal training.
Level 5 is if English is your second language but you are fluent. However, someone specially trained has to assess your competancy.
I think the levels decrease in ability so No.1 must be if you can grunt coherently and point in the right direction.
HD, is ATCO112's maturity based on your 30 years of experience in ATC.....................
yawn.