On AmigaOS filetype recognition was very sophisticated. There were several ways to do it: 1. Filemanagers allowed you to configure a full combination of tests,

On AmigaOS filetype recognition was very sophisticated. There were several ways to do it: 1. Filemanagers allowed you to configure a full combination of tests, which included magic bytes, binary or string seek to location and test for value, filename suffix, that all as often as liked, combined with boolean operators. 2. The system's datatypes.library had little slave drivers, that would "implement" a filetype, including any code a developer could write to do complex recognition. Modern filemanagers allowed to combine this with (1) 3. There was a shared function library (freeware), that did nothing but filetypes recognition, configurable by the user. How I miss these days...