I've come across S33 in a couple of contexts, both as a material spec. for stainless steel (part of BS1449) and as a project number for a modified Shorts C-class flying boat, optimised for transatlantic travel.
I think you may need to be more specific regarding the area the information you're after lies in.
Thanks for your response Rikman. This term is being used in the context of hiring preferences for structures work. It says simply "S33 preferred". I have training & experience in AC structural repair & maintenance but this term baffles me. I may just come out & ask them but I'd rather find out what it means on my own.
Yes, thanks ramesh75. I found out that it's actually a Canadian Dept of Transport certification that allows one to self inspect & pass one's own stuctural work. It's relativly new.