In PHP version 5.3 and higher, the backslash is used to indicate a namespace.
•
In the Japanese encodings ISO 646 (a 7-bit code based on ASCII), JIS X 0201 (an 8-bit code), and Shift JIS (a multi-byte encoding which is 8-bit for ASCII), the code point 0x5C that would be used for backslash in ASCII is instead rendered as a yen mark (¥), while in Korean encoding, it is drawn as a won currency symbol (₩).
•
In many programming languages such as C, Perl, and PHP and in Unix scripting languages, the backslash is used to indicate that the character following it should be treated specially (if it would otherwise be treated normally), or normally (if it would otherwise be treated specially).
He also served, with Hugh McGregor Ross and others, on the separate committee which defined the ASCII character codeset in 1960, contributing several characters which had not previously been used by computers including the ESCape character, the backslash character, and the curly bracket characters.
Not all of them encode the standard the same way, like replacing the typical backslash at byte 0x5C with the won currency sign (₩).