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Comment by mettamage | Hacker News Reader

Note: it's simply the wiki page, but in all my years that I read .epub files I never bothered to check the wiki page. So it is to my surprise I found out that it's just some XML and HTML/CSS!

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I had the same reaction when I found out word docx files are just zip files with a bunch of xml in there.

You might be surprised to learn just how many files are zip files.

Java software (jar, war): zip files

Android packages (apk): zip files

OpenDocument Format (odt, ods, odp): zip files

Quake 3 / OpenArena / Urban Terror / etc. (pk3): zip files

Firefox/Thunderbird/Chromium extensions (xpi, crx): zip files

EPUB: :D

Just look for that PK in the first 2 bytes of the file and it is a good chance it is a zip file. That jar/war one has saved me a few times in figuring out what exactly the compiler did to a program.

Yeah, it is surprising at first, but after you think about it, maybe not so much.

If you need to cram a bunch of files into one package, zip is the obvious candidate. There are well-tested libraries and apps for dealing with zips for essentially every language and operating system.

As the saying goes, "don't mess with success".

numpy's npz is also zip.

Docx was Microsoft's answer to the Open Document Format used by OpenOffice, which is also just zipped XML files.

cool.

To Downvoters: So there is something wrong with saying 'cool'? What is the problem this time? There is nothing malicious or 'offensive' than reacting to something by saying 'cool'. Come on.

Care to explain yourselves this time?

I didn't downvote, but it's a low-effort comment that doesn't really add anything to the discussion. There is no information, no argument, no widening of context, no additional perspective, nothing. It also isn't an acknowledgement-type reply like "I see" ending a discussion. In other words, it decreases signal-to-noise ratio. You can compare it to "congrats" email chains at corps.

EDIT: It would be ok in a live discussion. But on a forum, not so much.

The HN equivalent of a “cool” response is clicking the upvote button.

Excuse me?

Am I 'not allowed' to express my own opinion of this post via typing in text, even if it says 'cool'.

I think I am getting tone-policed.

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