SSL, BCV and JNP are/were the three divisions the infrastructure maintenance was split into for PPP named for the lines they would look after (generally speaking at least). SSL = Sub-surface Lines BCV = Bakerloo, Central and Victoria JNP = Jubilee, Northern and Piccadilly
Metronet won the SSL and BCV contracts, Tubelines won the JNP contract.
I can't help with P-CRID.
edit: PPP = Public-Private Partnership, the ill-fated outsourcing of London Underground maintenance.