.------------.   .-----------.                 .----------.   .------.
 | Registrant |   | Registrar |                 | Registry |   | TMDB |
 '------------'   '-----------'                 '----------'   '------'
        |     Request DN |                            |            |
        |   registration |                            |            |
        |--------------->|     Check DN availability  |            |
        |                |--------------------------->|            |
        |                | DN unavailable      .-------------.     |
        | DN unavailable |<-------------------( DN available? )    |
        |<---------------|                  no '-------------'     |
        |                | DN available               | yes        |
        |                |<---------------------------|            |
        |                |         Request lookup key |            |
        |                |--------------------------->|            |
        |                |.__________.           .---------.       |
        |                || CONTINUE |          /  Does DN  \      |
        |                || NORMALLY |<--------(  match DNL  )     |
        |                |'----------'       no \  of PRM?  /      |
        |                |                       '---------'       |
        |                | Lookup key                  | yes       |
        |                |<----------------------------'           |
        |                |                                         |
.-----. |                |                             Request TCN |
|ABORT| | Display        |---------------------------------------->|
'-----' | Claims         | Return TCN                              |
 ^      | Notice         |<----------------------------------------|
 | no   |<---------------|                                         |
 |  .------.  yes        |                                         |
 '-(  Ack?  )----------->|   Register DN (with TCNID) |            |
    '------'             |--------------------------->|            |
        | Registration   | Error         .----------------------.  |
        | error          |<-------------( Validation successful? ) |
        |<---------------|            no '----------------------'  |
        |                |                            | yes        |
        |                | DN registered              |            |
        | DN registered  |<---------------------------|            |
        |<---------------|                            |            |