2.1.2 [CSS-Level2-2009] Section 4.1.3, Characters and case


The specification states:

Note: Backslash escapes are always considered to be part of an identifier or a
 string (i.e., "\7B" is not punctuation, even though "{" is, and "\32" is allowed 
at the start of a class name, even though "2" is not). 
The identifier "te\st" is exactly the same identifier as "test".

All Document Modes (All Versions)

Backslash escapes are not processed when specifying the url() function name. For example, u\75l('myimage.png') does not resolve to url('myimage.png').