# Transaction IDs

STID

The Server Transaction ID (STID) ensures that the request from the RegAcc and the pertinent response of the RRI server can be referenced globally and uniquely for data writing requests. The STID is assigned by the RRI.

CTID

The Client Transaction ID (CTID) is optional and is assigned by the client (RegAcc) for all write-requests

The CTID must be unique and 3 to 64 characters long. The CTID corresponds to a sequence of characters chosen by RegAcc itself and may only be used once per RegAcc within 24 months. If the CTID is used again within the 24 months, the order will be rejected with an error.

You can use the CTID to assign requests and replies to each other. The following rule applies: The CTID is only included in the reply from the server if the .de registration system was able to parse the request.