xml - Regular expression p{L} and p{N}

Question

I am new to regular expressions and have been given the following regular expression:

(p{L}|p{N}|_|-|.)*

I know what * means and | means "or" and that escapes.

But what I don't know what p{L} and p{N} means. I have searched Google for it, without result...

Can someone help me?

Answer 1

p{L} matches a single code point in the category "letter".
p{N} matches any kind of numeric character in any script.

Source: regular-expressions.info

If you're going to work with regular expressions a lot, I'd suggest bookmarking that site, it's very useful.