I came across a similar thing in the mid 1990s. The program had been written in the late 1980s, and the original author had since died, so he couldn't be consulted. In those days memory was scarce, so the program had been "compacted" by removing all spaces and with all variables represented by single characters. The original non-compacted source code had disappeared along with its originator. For any practical purpose, the whole program was unreadable.