Don't completely rule out EBCDIC from the equation. It's generally an IBM-ism meant for punched cards with the same characters as ASCII. Despite the similarity,

Don't completely rule out EBCDIC from the equation. It's generally an IBM-ism meant for punched cards with the same characters as ASCII. Despite the similarity, it means that it's a legacy system kept alive to now and switching to UTF-EBCDIC would likely incur disturbing 70+ year old layers of tech debt dust. Some of them don't even support lower case characters as it's using EBCDIC's predecessor, BCD.