[mschuster91]

> 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?

Probably because, like many other ancient document formats (e.g. MS Office), it was a straight dump of memory structures into a file [1]. Obviously a very bad idea in hindsight (especially given the truckload of deserialization vulns resulting from it), but computers from that age were so memory-constrained that anything else wouldn't cut it, and by the time computers got more powerful the old formats were hopelessly entrenched.

[1] https://www.joelonsoftware.com/2008/02/19/why-are-the-micros...

[samus]

Flash and PDF have the same illnesses. Suspiciously many Adobe file formats are both overly complicated and contain lots of features that are way too powerful in combination and impossible to support properly.