We are using OpenXML to setup and process an excel file. It seems you can have multiple dataValidation rules in there with their own SequenceOfReferences (or ReferenceSequence depending on version) but when I attempt to test it in the produced file, only the first validation works. If I do the same with ConditionalFormatting, that works as expected. In our case, I basically need a dropdown list AND validation so they only use an item once per row. 1) Does excel not allow more than one dataValidation rule on a single cell? and 2) any ideas on how to apply both rules PER ROW ?