Not all changes of transaction type are possible because of data which is affected by the change, but if you log in to HLMSW using the Administrator key (which is generated from the \Administrator\Save Administrator Key menu option in the HLMSW Configuration Editor) does allow you to make changes to the data which are not normally permissible. These include editing an invoice that has already been printed, and change the transaction type.
If you do use the Administrator key to make any changes, it is important to make the changes and log off, as you can damage the integrity of the HLMSW data if you use this key for anything other than special purposes.
Peter (BTMI)