USV would have the disadvantage of using multi-byte characters as delimiters, so you have to decode the file in order to separate records. And you still can’t type the characters directly or be guaranteed to display them without font support. This honestly seems like cleverness for cleverness’s sake.

Ah fair enough. Of course you could configure your shell/editor/whatever to make control characters visible. Seems like if you were going to edit USV or ASV by hand you'd probably want a customized editor anyway.

The way I would have gone would be to define the standard to support both, such that the two sets of codes MUST be considered semantically equivalent, but that generation tools SHOULD prefer to generate the control codes for new files.

This way people can initially use the visible glyphs while editors don't support the format, and this will always be supported. But, as editors add support and start to generate the files via tools or manually in tabular interfaces where the codes themselves disappear, usage will automatically transition over to the control codes.

This is so weird, since the purpose of the former characters is displaying the latter characters. If they are actually used for display, then you can’t tell which is which.