Introduction¶

The Linux kernel code has been rewritten to use Unicode to mapcharacters to fonts. By downloading a single Unicode-to-font table,both the eight-bit character sets and UTF-8 mode are changed to usethe font as indicated.

This changes the semantics of the eight-bit character tables subtly.The four character tables are now:

In particular, ESC ( U is no longer “straight to font”, since the fontmight be completely different than the IBM character set. Thispermits for example the use of block graphics even with a Latin-1 fontloaded.

Note that although these codes are similar to ISO 2022, neither thecodes nor their uses match ISO 2022; Linux has two 8-bit codes (G0 andG1), whereas ISO 2022 has four 7-bit codes (G0-G3).

In accordance with the Unicode standard/ISO 10646 the range U+F000 toU+F8FF has been reserved for OS-wide allocation (the Unicode Standardrefers to this as a “Corporate Zone”, since this is inaccurate forLinux we call it the “Linux Zone”). U+F000 was picked as the startingpoint since it lets the direct-mapping area start on a large power oftwo (in case 1024- or 2048-character fonts ever become necessary).This leaves U+E000 to U+EFFF as End User Zone.

[v1.2]: The Unicodes range from U+F000 and up to U+F7FF have beenhard-coded to map directly to the loaded font, bypassing thetranslation table. The user-defined map now defaults to U+F000 toU+F0FF, emulating the previous behaviour. In practice, this rangemight be shorter; for example, vgacon can only handle 256-character(U+F000..U+F0FF) or 512-character (U+F000..U+F1FF) fonts.

Actual characters assigned in the Linux Zone¶

In addition, the following characters not present in Unicode 1.1.4have been defined; these are used by the DEC VT graphics map. [v1.2]THIS USE IS OBSOLETE AND SHOULD NO LONGER BE USED; PLEASE SEE BELOW.

The DEC VT220 uses a 6x10 character matrix, and these characters forma smooth progression in the DEC VT graphics character set. I haveomitted the scan 5 line, since it is also used as a block-graphicscharacter, and hence has been coded as U+2500 FORMS LIGHT HORIZONTAL.

[v1.3]: These characters have been officially added to Unicode 3.2.0;they are added at U+23BA, U+23BB, U+23BC, U+23BD. Linux now uses thenew values.

[v1.2]: The following characters have been added to represent commonkeyboard symbols that are unlikely to ever be added to Unicode propersince they are horribly vendor-specific. This, of course, is anexcellent example of horrible design.

Klingon language support¶

In 1996, Linux was the first operating system in the world to addsupport for the artificial language Klingon, created by Marc Okrandfor the “Star Trek” television series. This encoding was lateradopted by the ConScript Unicode Registry and proposed (but ultimatelyrejected) for inclusion in Unicode Plane 1. Thus, it remains as aLinux/CSUR private assignment in the Linux Zone.

This encoding has been endorsed by the Klingon Language Institute.For more information, contact them at:

http://www.kli.org/

Since the characters in the beginning of the Linux CZ have been moreof the dingbats/symbols/forms type and this is a language, I havelocated it at the end, on a 16-cell boundary in keeping with standardUnicode practice.

Klingon has an alphabet of 26 characters, a positional numeric writingsystem with 10 digits, and is written left-to-right, top-to-bottom.

Several glyph forms for the Klingon alphabet have been proposed.However, since the set of symbols appear to be consistent throughout,with only the actual shapes being different, in keeping with standardUnicode practice these differences are considered font variants.

Other Fictional and Artificial Scripts¶

Since the assignment of the Klingon Linux Unicode block, a registry offictional and artificial scripts has been established by John Cowan<jcowan@reutershealth.com> and Michael Everson <everson@evertype.com>.The ConScript Unicode Registry is accessible at:

http://www.evertype.com/standards/csur/

The ranges used fall at the low end of the End User Zone and can hencenot be normatively assigned, but it is recommended that people whowish to encode fictional scripts use these codes, in the interest ofinteroperability. For Klingon, CSUR has adopted the Linux encoding.The CSUR people are driving adding Tengwar and Cirth into UnicodePlane 1; the addition of Klingon to Unicode Plane 1 has been rejectedand so the above encoding remains official.