Agree Although I don t know much about the standard but from the text The OpenDocument Format 1 0 1 1 specifications refer to ZIP files but do not reference a standard which describes the zip file format The specifications just refer to ZIP which is not supposed to be included in the spec It is hardly to say it s a related criticism to ODF IMO Similarly it is hardly to say a book is bad just because it doesn t give a clear picture of what it refers to It s acceptable to leave the ZIP unspecified undefined