TOKEN IDENTIFIER (TID) ROLLOVER
The Token Identifier is a 24 bit field, contained in STS compliant tokens, that identifies the date and time of the token generation. It is used to determine if a token has already been used in a payment meter. The TID represents the minutes elapsed since the 1st January 1993. The incrementing of the 24 bit field means that at some point in time, the TID value will roll over to a zero value.
All STS prepayment meters will be affected by TID roll over on the 24/11/2024. Any tokens generated after this date and utilizing the 24bit TID will be rejected by the meters as being old tokens as the TID value embedded in the token will have reset back to 0.
In order to overcome this problem all meters will require key change tokens with the roll over bit set. In addition to this, the base date of 01/01/1993 will be required to be changed to a later date. This process will force the meters to reset the TID stack to 0. To avoid previously played tokens from being accepted by the meter due to the TID stack reset, the key change process must introduce into the meter, a new decoder key.
A process is therefore required to allow for the management of this change with the least impact to the Utilities and equipment suppliers.
For more information on the TID rollover, please see the [STS402-1] Code of Practice.
Please click here for the TID Rollover microsite.