When the Integration Service runs in ASCII mode, the external procedure can process data in 7-bit ASCII. When the Integration Service runs in Unicode mode, the external procedure can process data that is two-way compatible with the Integration Service code page.
Configure the Integration Service to run in Unicode mode if the external procedure DLL or shared library contains multibyte characters. External procedures must use the same code page as the Integration Service to interpret input strings from the Integration Service and to create output strings that contain multibyte characters.
Configure the Integration Service to run in either ASCII or Unicode mode if the external procedure DLL or shared library contains ASCII characters only.