big-endian

A byte ordering that stores a number's most significant byte first.

Endianness is the order in which a multi-byte number's bytes are laid out in memory; big-endian puts the biggest-value byte first, the reverse of little-endian used by most PCs. Formats like network protocols and Device Tree Blobs (DTBs) are big-endian, so a parser must convert bytes correctly or read garbage. 'Proper big-endian handling' means honoring that order when reading such data.