Well they're not special "codes". What you've pasted is
UTF-8 encoded text, which means that as long as users have a UTF-8 capable IRC client (which mIRC is, provided the "UTF-8 display" option is turned on), they will see that text as five
Unicode characters:
U+0e51 (Thai digit one)
U+06e9 (Arabic Place of
Sajdah)
U+06de (Arabic Start of
Rub El Hizb)
U+06e9 (Arabic Place of
Sajdah)
U+0e51 (Thai digit one)
Of course on non-UTF-8 capable IRC clients they appear as a mess of ASCII (or whatever the client's supported encoding is) characters.
The important thing to realise is that there's nothing magical or special about those characters, they're just UTF-8 encoded text, which supports characters, symbols, and other glyphs for thousands of different languages.
