This will make a difference how we write regexes. Look at the level 1 properties: [\p{letter} \p{decimal number}] And compare for instance to the POSIX reg

This will make a difference how we write regexes. Look at the level 1 properties: [\p{letter} \p{decimal number}] And compare for instance to the POSIX regexp character classes (a reference: https://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Basic_Regular_Expressions#Character_classes https://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Basi...) [[:alpha:] [:digit:]] Given that the Unicode standard goes much beyond, proper implementations should help to write regexps for the modern web, encountering problems we are typically faced with. It's a pity the standard goes not into detail there, thought (for instance, similiarity of characters).