Pipe Chars in HTML Classes

I couldn't find anything in the W3C docs that said pipe chars, |, aren't allowed, for instance:

<div class="c开发者_JAVA技巧lass1|class2">

Don't worry about what I might be using it for. I was just wondering if it's "legal".

The relevant rules can be found in w3c syndata tokenization section, though it's pretty difficult to conclude from there if pipe is valid or not, as per a glance, it seems that anything is valid for a selector, i.e.:

selector    : any+;
any         : [ IDENT | NUMBER | PERCENTAGE | DIMENSION | STRING
              | DELIM | URI | HASH | UNICODE-RANGE | INCLUDES
              | DASHMATCH | ':' | FUNCTION S* any* ')' 
              | '(' S* any* ')' | '[' S* any* ']' ] S*;

It's legal HTML, since the datatype of class is CDATA. You will have a problem with CSS selectors, because the pipe is not a valid character for a selector.

It is a valid character in a class name. In fact, I see a website using pipe ( | ) just for the sake of class separation. Which I think is a good practice for readability.