All this complexity is true of a number of legacy (bad) text protocols. DNS zone files for example are specified incredibly poorly despite their apparent simpl

All this complexity is true of a number of legacy (bad) text protocols. DNS zone files for example are specified incredibly poorly despite their apparent simplicity (multiple optional ambiguous fields, significant whitespace, poorly specified line-folding and paren semantics, DNS record-type dependent record value grammars, vaguely specified length limits, lexical includes, embedded parsing directives, it goes on...). You won't find any 2 implementations that behave the same. It's typical to talk to engineers who haven't been through serious parser work and get responses like "well, it's just splitting a few strings isn't it?"