What difference to this make to my data pump

Once you've enabled the Multiphase data pump you get a few more options in the transformations tab of the data pump. Figure 1.2 shows the new choices you have.

Figure 1.2 Transformation Choices.

If you remove all the predefined transformations that DTS gives you and add a new one and select ActiveX as the type then you'll go through to the usual scripting screen. The difference is the Phases tab. Select it and in here you can start to define the functions that will handle each phase of the transformation. In Figure 1.3 we've already entered some functions which simply pop up a message box when that phase is triggered. You can enter your own into the rest of the possible phases.

Figure 1.3 Phases Tab.