read twice the post: if "internal description of .npk file"
Starting offset 0x20 (114)
for example on v6 mibsbe is
and each platform have it's own string
instead on v7 REGARDLESS THE PLATFORM
is padding 0x00
you can not do any, the .npk files are digitally signed, and if you alter something, routeros do not install it (if the dude recognize it or not, not mind)