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In your macro in C# code you can e.g. check the DocumentSKUName column. It will be empty for non-SKU or filled with some name in case it is representing the SKU. So you can test its length. Your macro could return 0 or 1 based on if the document represents SKU.
Then in the transformation you might want to use conditions like:
<%# IfCompare(1, 2, "The values are different", "The values are equal") %>