为什么SQL Server 2008的新T-SQL在兼容模式80下对数据库起作用？

Experimenting with new features of T-SQL, I've run into a puzzle. Here is some new syntax supported by SQL 2008 and I'd expect it to work on databases set for compatibility mode 100 (i.e. 2008) and not work for compat mode 80 (i.e. 2000). Yet this works for a database set for SQL SERVER 2000 compatibility mode on a SQL 2008 instance of Standard edition:Experimenting with new features of T-SQL, I've