| 101 | Registration submission | 
|  | Submission of information for registration. | 
| 102 | Asymmetric key pair request | 
|  | Request a trusted party to generate an asymmetric key pair. | 
| 110 | Certification request | 
|  | Request certification of credentials and public key. | 
| 111 | Certificate renewal request | 
|  | Request to extend the validity period of the current valid key, whose certificate is about to expire. | 
| 112 | Certificate replacement request | 
|  | Request to replace the current certificate by a new one with a different public key (and possibly other information). | 
| 121 | Certificate (path) retrieval request | 
|  | Request the delivery of an existing (valid or revoked) certificate, with path details where appropriate. | 
| 123 | Certificate list retrieval request | 
|  | Request full or partial list of certificate. | 
| 124 | Certificate status request | 
|  | Request current status of a given certificate. | 
| 125 | Certificate validation request | 
|  | Request the CA to validate an existing certificate. | 
| 126 | Certificate delivery request | 
|  | Request the CA to deliver a (valid or revoked) certificate to a list of recipients known to the CA or specified elsewhere. | 
| 130 | Revocation request | 
|  | Request revocation of a party's certificate. | 
| 131 | Alert request | 
|  | Request to put a party's certificate on alert. | 
| 140 | Revocation list request | 
|  | Request full or partial list of revoked certificates. | 
| 150 | Symmetric key request | 
|  | Request the delivery of symmetric keys. | 
| 151 | Symmetric key discontinuation request | 
|  | Request discontinuation of symmetric key. | 
| 152 | Asymmetric key discontinuation request | 
|  | Request discontinuation of asymmetric key. | 
| 221 | Certificate delivery | 
|  | Delivery of an existing (valid or revoked) certificate. | 
| 222 | Certificate path delivery | 
|  | Delivery of a path. | 
| 224 | Certificate status notice | 
|  | Notice of current status of a given certificate. | 
| 225 | Certificate validation notice | 
|  | Notice of validation of an existing certificate. | 
| 231 | Revocation confirmation | 
|  | Confirmation of revocation of a party's certificate. | 
| 251 | Symmetric key delivery | 
|  | Delivery of symmetric keys. | 
| 252 | Discontinuation acknowledgement | 
|  | Acknowledgement of the requested discontinuation. |