A user transaction is a sequence of forms that establish a dialog with a user; a dialog that terminates only when there are no more forms in the sequence. A Transaction Postprocessor is a script that is called when one of the individual forms is submitted. It can validate the input, modify the or interpret the values, determine if the transaction continues or terminates, and may alter set which form ts next ion the sequence. It can also perform whatever actions are appropriate, such as send an email, add a member to a membership group, interact with an external database or complete a financial transaction. The only practical limitation is that it should respond to the user quickly enough to maintain the interactivity of the transaction. Postprocessors are assigned to user transaction forms by Managing Editors, by setting a form option, see On submit. addedValues ships with several postprocessors, which serve as models of how programmers can create their own postPorocessors without too much difficulty.