Like ASCII, Unicode is a character set, but it also includes a set of rules for representing, manipulating, interpreting, and comparing strings. Unicode strings are built from code points which can be encoded in various ways including UTF-32, UTF-16, and UTF-8. Unlike ASCII, code points interact with each other in carefully prescribed ways. Unicode can be used to represent character sets outside of the normal ASCII range, such as Chinese, Japanese, Korean, Cherokee, Tibetan and even fictional/constructed languages and writing systems, such as Klingon and Tengwar.
Support in Servers and Clients
At present, MUX2 is the only MUSH-variant which supports Unicode characters on a game, with Unicode support having been added in the 2.7 line.
To make use of the Unicode support, a Unicode-aware client is required; clients we currently know of include Atlantis, KildClient and (to a limited extent) MushClient.
Using Unicode in your Client
Atlantis (Mac OS X)
Atlantis requires no additional configuration; if you connect to a Unicode-aware MUX, the Unicode support is automatically negotiated. It will use any available glyphs it can from all installed fonts, and allows Unicode to be entered in the input window as well.
To use Unicode on a Unicode-aware MUX with KildClient, you must go into the 'Miscellaneous' section of the world settings and set the character set to 'UTF-8' first. Once connected, you must then @set yourself UNICODE. Once this is done, KildClient supports Unicode fully, picking glyphs from available fonts and allowing you to input Unicode characters in the input section.
To use Unicode on MushClient, you must pick a Unicode capable font (Lucida Console is generally chosen) and turn on the 'UTF-8' checkbox in the settings for the world. Once this is done, MushClient will negotiate the Unicode support automatically. Limitations of MushClient's support include that Unicode characters cannot be entered into the input window to be sent, and that characters not included in the Unicode capable font you've chosen may be omitted.
TinyFugue (Linux/UNIX console)
No support. However, TF generally lets most things pass through unchanged. It's possible to setup both ends so that stuff gets through, but TinyFugue has no understanding of it, and it steps on some characters.
Potato MUSH Client (Linux/Windows)
Full support for Unicode including automatic opt-in negotiation. Written in Tcl.