I was at that very page in SQL 10 Books Online:

http://msdn2.microsoft.com/en-us/library/bb677290(SQL.100).aspx

And I quote:

"The hierarchyid data type is a variable length, system data type."

and

"The hierarchyid type is available to CLR clients as the SqlHierarchyId data type."

Does the fact that the hierarchy type has methods mean it is a CLR type? That would be the only clue I could see in that article that it is a CLR type. The article never explicitly says that.

I always have trouble reading between the lines. I always need things said explicitly.

):-D