The least fun csv-like format i have seen was mandated by a Big Spanish Bank. It was original a fixed fieldwith flatfile. Numerals were 0-leftpadded and fixed d

The least fun csv-like format i have seen was mandated by a Big Spanish Bank. It was original a fixed fieldwith flatfile. Numerals were 0-leftpadded and fixed decimal (decimal point not written). Except that someone decided they needed to open it in Excel so semicolons were added at the end of each field. Then they discovered that some data didn't actually fit in the fixed with fields. So certain fields where variable width. End result was a file that looked like shit in Excel, and couldn't be parsed by a fixed width parser.