What I'm doing is, I suppose, a variation of the declarative marking, but not quite the same. I'm not having trouble with the XML format, but rather with the method signatures in the rules section. Some parameter types seem to just use the reflection type names, such as System.TimeSpan, but others, like System.Double, get their own special-cased name like float64. I just want to make sure I can capture all of those special cases, or better yet understand the logic behind them.