A FrameMaker-generated index includes, for every <$nopage> entry, a link to the original marker location in the document. The Sundorne Communications IndexRef plug-in can change the links for <$nopage> See and See also entries in FrameMaker, so the links point to the referenced index entries instead. See:
When you convert a generated index to Word, Mif2Go converts any IndexRef-created links properly. If you do not use IndexRef, links for See and See also entries in Word point to the original location of the <$nopage> index markers in your document.