PowerBuilder Native Interface Programmers Guide and Reference
Exchanging Data with PowerBuilder

You can use the IPB_Session interface or the IPB_Value and IPB_Arguments interfaces to exchange data between PowerBuilder and PBNI. The IPB_Session interface contains many virtual functions that enable the C++ code in an extension to interact with the PBVM. The IPB_Value and IPB_Arguments interfaces contain methods that you can use to pass values between PowerBuilder and extensions.