There was/is no RFC for the ZIP file format (there is for gzip and the DEFLATE algorithm). It was Phil Katz releasing a text file called APPNOTE.TXT describing

There was/is no RFC for the ZIP file format (there is for gzip and the DEFLATE algorithm). It was Phil Katz releasing a text file called APPNOTE.TXT describing the file structure (latest version is available at https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT ).