I'm writing to web services and need to signify that a value is null using the attribute xsi:nil="true" rather than leaving an empty tag or no tag. I can add the attribute to the xml elements and just change the values between true and false but it's messy because xsi:nil="false" is unnecessary because the receiver can figure out that the tag isn't null if it's not set to true. Is there a cleaner way to do this?