The BPSS is the entry-level National Security Clearance, and both CTC and EBS are effectively enhancements to the BPSS, with CTC relating to checking for susceptibility to extremist persuasion, and EBS relating to checking for susceptibility to espionage persuasion, the latter being needed for supervised access to SECRET material. The SC again is focused on susceptibility to espionage persuasion, and is required for an individual to have long-term unsupervised access to SECRET material and occasional access to TOP SECRET (TS) material, whilst for regular access to TS the DV is required.