The problem is not that the reading method should be obvious once you consider that era, but that the reading or writing method is not exactly specified and the

The problem is not that the reading method should be obvious once you consider that era, but that the reading or writing method is not exactly specified and there can be a considerable variety in implementations. For example the OP complains about a passing mention (4.3.1): > Files MAY be added or replaced within a ZIP file, or deleted. While the author considers this to imply (but not acknowledge) that local file headers and central directory headers may disagree to each other, I'm not even sure because the specification never clearly confirms whether a random data can appear before any local file header. The only thing that has been acknowledged is SFX (4.1.9), and it is not even specified where the "extraction code" can be embedded. Can it be placed between two files? If such thing is indeed possible, shouldn't there be a provision to avoid ambiguity due to the stray data? Say, it could have said that deleting a file in place should mask all occurrences of local file header signature 0x04034b50 so that the vacant space can no longer interpreted as a file at all.