A term which describes a system that deals correctly with extended character sets which (unlike ASCII) use all eight bits of a byte. Many programs and communications systems assume that all characters have codes in the range 0 to 127. This leaves the top bit of each byte free for use as a parity bit or some kind of flag bit. These assumptions break down when the program is used in some non-english-speaking countries with larger alphabets.
If a binary file is transmitted via a communications link which is not eight bit clean, it will be corrupted. To combat this you can encode it with uuencode which uses only ASCII characters. There are some links however which are not even "seven bit clean" and cause problems even for uuencoded data.
(05 Jan 1995)