KOI character encodings
KOI (Russian: КОИ, from код обмена информацией, kod obmena informatsiey, 'code for information exchange') is a family of several code pages for the Cyrillic script. A particular feature of the KOI code pages is that the text remains human-readable when the leftmost bit is stripped, should it inadvertently pass through equipment or software that can only deal with 7 bit wide characters.