Standard Transfer Specification Association
Standard Transfer Specification Association


In the STS domain a token can be defined as a message containing data to be sent to a payment meter via several possible carrier types. The following token types are defined in the IEC62055-41 specification:

Credit tokens (Class 0)

Credit tokens a a class of tokens used to carry credit from a Point of Sale to a payment meter. Several subclasses of these tokens are available for use:

Unit based tokens

Unit based tokens transfer utility units in the following categories:

 ​Token TypeSub-class​​Utility Units​
​Electricity credit 0 0.1 kilowatt-hours​
Water Credit 1 0.1 cubic meters
Gas Credit 2 0.1 cubic meters
​Time Credit 3 0.1 minutes

Currency based tokens

Currency based tokens transfer currency amounts in the following categories:

Token TypeSub-classCurrency Units​
Electricity Currency 40.00001 base currency units
Water Currency 50.00001 base currency units
​Gas Currency 60.00001 base currency units
Time Currency 70.00001 base currency units

This token type is useful when a payment meter makes use of complex tariffs such as time-of-use tariffs, where the cost of the utility depends upon the time of day. The currency denomination is not defined, therefore allowing the utility to taylor it for their currency type. The resolution is 0.00001 base units, allowing for most currency denominations.

Non meter specific management tokens (Class 1)

​This token class defines the following tokens:

Token Type



Test token (2-digit man code)


varies depending on test selected

Test Token (4-digit man code)


varies depending on test selected

Extended token read


0 - 63

Proprietary tokens

6 - 15

Not defined

These tokens are not encrypted by the POS system since they are not unique to a specific meter but will work in any STS compliant meter. These tokens may be hardcoded into the POS system since they do not change. Care should be taken however, to ensure that both the 2 - digit and 4 - digit manufacturer code tokens are available on the POS system since they differ depending on the number of digits in the manufacturer code of the meter.

​Meter specific management tokens (Class 2)

The meter specific management tokens are used to set parameters in the payment meter, as well as perform key-change operations on the payment meter. These tokens include:
  • Key-change tokens - Tokens used to update the decryption key in the meter.
  • Maximum Power limit tokens - Tokens used to change the maximum power that the meter may supply. 
  • Clear Credit tokens - Tokens used to clear the existing credit in the meter.
  • Maximum Phase Power Unbalance Limit tokens - Tokens used to set the maximum unbalance between phases

Reserved tokens (Class 3)

This token class is reserved by the STS Association and must not be used in payment meters, or generated by the POS.

References: IEC62055-41 Ed2