Structured formats cannot natively represent every possible type. For example JSON might support very basic types, like integers and booleans, but not more comp

Structured formats cannot natively represent every possible type. For example JSON might support very basic types, like integers and booleans, but not more complex types like date/time types. Formats like JSON only have an advantage when discussing built-in types. Because with JSON, if you say "this field is a boolean" then everyone knows its possible values, however, if you say "this field is a date" then who knows? The point the article makes is the format itself shouldn't dictate types and to let the application decide them - which it what happens anyway for types the format doesn't natively support. You need documentation either way.