Many thanks to tachyon, TilRMan, jZed and others for the helpful responses! Yes, this is an ancient ('70's era) app that has its own bizarre (but consistent) logic for maintaining these files. Unfortunately, it does allow for both commas and quote characters within quoted text fields, which is why I didn't want to get into the business of writing my own parser.

As I mentioned, I do have file layouts detailing the datatypes of each field I'm going to encounter. I think the approach I'll take will be to read the file layouts into a data structure, and re-quote the text fields when they're in an array. That way I can still use the well-tested Text::CSV or Text::CSV_XS for parsing and rewriting the CSVs. It'll take more work, but that's probably the most bulletproof and flexible approach.

Again, thanks!

-E