https://github.com/zepouet/Xee-xCode-4.5/blob/master/XeePhotoshopLoader.m#L108

// At this point, I'd like to take a moment to speak to you about the Adobe PSD
// format. PSD is not a good format. PSD is not even a bad format. Calling it
// such would be an insult to other bad formats, such as PCX or JPEG. No, PSD
// is an abysmal format. Having worked on this code for several weeks now, my
// hate for PSD has grown to a raging fire that burns with the fierce passion
// of a million suns.
//
// If there are two different ways of doing something, PSD will do both, in
// different places. It will then make up three more ways no sane human would
// think of, and do those too. PSD makes inconsistency an art form. Why, for
// instance, did it suddenly decide that *these* particular chunks should be
// aligned to four bytes, and that this alignement should *not* be included in
// the size? Other chunks in other places are either unaligned, or aligned with
// the alignment included in the size. Here, though, it is not included. Either
// one of these three behaviours would be fine. A sane format would pick one.
// PSD, of course, uses all three, and more.
//
// Trying to get data out of a PSD file is like trying to find something in the
// attic of your eccentric old uncle who died in a freak freshwater shark
// attack on his 58th birthday. That last detail may not be important for the
// purposes of the simile, but at this point I am spending a lot of time
// imagining amusing fates for the people responsible for this Rube Goldberg of
// a file format.
//
// Earlier, I tried to get a hold of the latest specs for the PSD file format.
// To do this, I had to apply to them for permission to apply to them to have
// them consider sending me this sacred tome. This would have involved faxing
// them a copy of some document or other, probably signed in blood. I can only
// imagine that they make this process so difficult because they are intensely
// ashamed of having created this abomination. I was naturally not gullible
// enough to go through with this procedure, but if I had done so, I would have
// printed out every single page of the spec, and set them all on fire. Were it
// within my power, I would gather every single copy of those specs, and launch
// them on a spaceship directly into the sun.
//
// PSD is not my favourite file format.