Schema questions

I had a couple of questions on the schemas that we pulled out of the schema repository:

- DistanceType doesn't allow any content and the only attribute for it is the units of measure. The elements derived from it don't extend it to add content. So, how do I specify a distance?

- Why is it that BinarySpatialOpType, BinaryOperatorType, BinaryComparisonOpType all have only two arguments, but BinaryLogicOpType allows an unbounded number of arguments (min of 2)? If it's not really binary, wouldn't a different name be in order?

Thanks for the help. I'm sure I'll have more questions later.