Here are the data structures with brief descriptions:
  PKCS11_cert_st | PKCS11 certificate object |
| PKCS11_ctx_st | PKCS11 context |
| PKCS11_key_st | PKCS11 key object (public or private) |
| PKCS11_slot_st | PKCS11 slot: card reader |
 PKCS11_token_st | PKCS11 token: smart card or USB key |
