.------------.     .-----------.                 .----------.
| Registrant |     | Registrar |                 | Registry |
'------------'     '-----------'                 '----------'
       |                 |                             |
       |      Request DN |                             |
       |    registration |                             |
       |      (with SMD) |                             |
       |---------------->|       Check DN availability |
       |                 |---------------------------->|
       |                 |                             |
       |                 | DN unavailable       .-------------.
       | DN unavailable  |<--------------------( DN available? )
       |<----------------|                   no '-------------'
       |                 |                             | yes
       |                 | DN available                |      
       |                 |<----------------------------|
       |                 |                             | 
       |                 |     Request DN registration |
       |                 |                  (with SMD) |
       |                 |---------------------------->|
       |                 |                             |
       |                 |             .------------------------------.
       |                 |             | DN registration validation / |
       |                 |             |       SMD validation         |
       |                 |             '------------------------------'
       |                 |                             |
       | Registration    |.-----------. Error .----------------------.
       | error           || TRY AGAIN |<-----( Validation successful? )
       |<----------------|| / ABORT   |    no '----------------------'
       |                 |'-----------'                | yes
       |                 |                             |
       |                 | DN registered               |
       | DN registered   |<----------------------------|
       |<----------------|                             |
       |                 |                             |