Why is the Stream.Position a long

I'm was messing around with some parsing of a binary file when I came across something I was wondering about.

The Stream.Positionproperty is of the type Int64or long. Why is this? Shouldn't it make more sense to use a UInt64 since the position in a stream can't be negative?

Anyone know what's the use of this being a signed long in开发者_如何学编程stead of an unsigned one?

UInt64 is not CLS Compatible, and all classes in the BCL need to be (at least on their public/protected stuff)

The real question is of couse why UInt64 isn't CLS Compatible, and that was already asked and answered :)