Usually something being "reserved" means it is not being used yet by the current version of a format.
What the numbers mean really depends on the specification at hand.
Could mean "at position 15 with a length of 9", for example.
Yes.
You can either use QFile::readAll() to get the full file content into a single byte array or use QFile::seek() to jump to a specific position and then use QFile::read() to read a number of bytes from that position onwards.
Cheers,
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