ИЗОТ ЕС 8531 М2КЛ
ЕС 8531 М2КЛ (Latin, “ES 8531 M2KL”) is the keyboard from the ES 8531.M2 from Bulgarian manufacturer ИЗОТ (IZOT). Depending what you read, this is either an IBM-compatible computer, simply a personal computer, or a programmable terminal for the ЕС-1035 (ES-1035). (“КЛ” itself is short for “клавиатура” (“klaviatura”), meaning “keyboard”; compare French “clavier”.)
The switches are Cherry M9. If this is the keyboard from which 10ko sourced his M9 switches (of which I have a few via UncleFan), then these will be M94A-1GBR, the M9 type found in Bulgaria. In which case, this may be a custom M9 type ordered by ИЗОТ, and this may explain why this M9 type is widely found there.
The keyboard is externally marked “Сделано в Болгарии” (“Made in Bulgaria”), and the example below is dated to 1987 from the rear label.
It would seem that every key is both relegendable and printed, but without closer inspection it is not possible to be sure.
The photos are from 10ko and were taken in 2019 (the EXIF data is incorrect).