PowerBuilder's initial support for version control systems required drivers for specific vendors (e.g., PVCS) and often for specific versions of that vendor's products. It was not unusual to find that you needed to wait to upgrade your source control product until PowerBuilder released an updated driver for it. And if your source control provider wasn't supported by PowerBuilder you were simply out of luck.
That changed with PowerBuilder 6. With that release, PowerBuilder abandoned the vendor specific drivers in favor of the recently introduced Microsoft Source Code Control Interface (MSSCCI). Essentially an ODBC for version control, it freed the IDE from vendor lock-in. Provide the source control provide provides an MSSCCI complaint interface, or there was a 'bridge' product available that could convert MSSCCI calls into the source control providers native API calls, PowerBuilder could use the product.