You mean POSIX isn't published?

You think it's by random chance that unix source code is to a large part movable between different Unix implementations about between different computer architectures?

Maybe you could explain the difference between Linux and maybe FreeBSD or NetBSD or Hurd/Mach or some other kernel? You, as end user, have no need to know what the original priorities were when any of them were started. What you need to know is what they deliver - and you can find huge amounts of documentation about that. There is documentation about what calls are available for the CRTL. There are documentations about the file system implementations. There are documentation about the memory subsystem. There are documentation about the schedulers. There are documentation about the device subsystem and any proc file system.

But there can't be a Linux product that documents the end result of taking a Linux kernel, combining it with X and a hundred other applications and making a complete OS distribution for a specific target hardware platform. That is documentation that must be done by the company who packages the system.

The systems I work with are using Linux. But with completely own packaging of the OS. So I have to write documentation about our specific configuration files used to specifically allow remote-configuration of thousands and thousands of embedded devices using central administrative servers. That has nothing to do with Linux. All to do with the specific product sold, and based on Linux, GNU and other software.

So how about you tell us what Linux documentation you miss. And don't continue that GETTY route. It's no more Linux than PuTTY is Windows. At least be specific enough and talk about a specific application used in a specific Linux packaging. Maybe some software available in a Debian release? It would still not be Linux, but would be used with Linux.