The Passback Function

This function assumes that you are familiar with CGI scripting.

Related Links: Lookup Function | Return Mode Function | Return Address | Recurring Postback | PGP

Read the RESTRICTIONS below before using this function. As always, test your forms before making them live.

The Passback Function enables you to include input variables in your order form that are passed back to your return address after the transaction is completed. This allows you to maintain user session, offer real-time delivery of software, access to member-only areas, etc. This function also allows information for successful orders to be written to an online database in realtime.

For example, you can pass an invoice number, customer identification, PIN numbers, and more, giving you complete control of the data received after a transaction completes.

To use the PASSBACK FUNCTION, simply add the passback fields to your order forms(s) as shown in the examples below. (You may include as many Passback variables as you would like.)

Note: You may select how these variables are returned to your return address by using the Return Mode Function. They will either be sent as part of the "query_string" or as name/value pairs from an HTML POST.


  • Field names used for the Lookup Function are reserved and may not be used as Passback field names. However, the Passback Function may be used to request the contents of each description, cost, and quantity.
  • Your ret_addr (return address) must be a script (such as Perl, PHP, ASP, CFM) that is capable of accepting and parsing variables posted from an HTML form.


In this example, the ret_addr field in the order form was set to "". This example shows variables returned as part of the query_string.

<input type="hidden" name="passback" value="fieldname1" />
<input type="hidden" name="fieldname1" value="12345" />

<input type="hidden" name="passback" value="ordernum" />
<input type="hidden" name="ordernum" value="order#999" />

After a successful order has been completed, the customer is returned to the following URL. (Orders are always signed with a PGP Signature when either the LOOKUP or PASSBACK fuction is used.) SIGNATURE HERE

You can use as many PASSBACK variables as necessary with whatever variable names you'd like. The above example uses two variables. They are named fieldname1 and ordernum.

Note: Each passback field must contain a value. If the field contains no value, you will receive a "nonexistant passback parameter" error.

If you would like to allow your customers to select a user name and password for access into your site, the Passback Variables may look like the following:

<input type="hidden" name="passback" value="username" />
<input type="text" name="username" />

<input type="hidden" name="passback" value="password" />
<input type="text" name="password" />

If the customer's order is successful, the user name and password will be passed back to you in the query_string.

**Please note that this example is not a secure method of allowing access into your site.