When using the three stage model (opposed to the two step model), the inital authorisation is split into two individual steps; first, a 'null-authorization' is done - the card is checked for creditability, but no money is reserved. Second, a normal authorization is done on the requested amount. This enables the money to be available to the customer untill the second authorization, but leads to the risk that at the time of the second authorization, the amount of money requested is not available even though the inital null-authorization was accepted.
To activate the three stage model, please take contact to our support department, but keep in mind that it will only work for Dankort/Visa-Dankort payments through Nets/Teller. Aside from activation on the DIBS account, the following functions can be used for carrying out the different stages; auth.cgi, suppl_auth.cgi (for the second authorization) and capture.cgi. Furthermore the remaining functions can be used as normally.