Named Character Classes In Regular Expressions.

[Laser Lu]

Hi, all,
Does any body recognize \p{name} in Regular Expression? In MSDN, it says
the \p{name} represents a named character class, the original description
is as follows:

"Matches any character in the named character class specified by {name}.
Supported names are Unicode groups and block ranges. For example, Ll, Nd,
Z, IsGreek, IsBoxDrawing."

I want to know whether those named character classes are predefined or not?
If they were not predefined, how to define a named character class that would
be referencable by the '\p{name}' mark? Thank you all:)

Best regards,
Laser Lu