For image (pixmap/bitmap) data, byte order is defined by the server, and clients with different native byte ordering must swap bytes as necessary. For all other parts of the protocol, the byte order is defined by the client, and the server swaps bytes as necessary.

The order of bytes in a binary representation of a number. When transmitted on the Internet, the most significant byte is first; for example, a 16-bit word representation of 256 would be 0x0100. On a host computer, such as an Intel computer, the least significant byte is first; for example, a 16-bit word representation of 256 would be 0x0010.

There are two main conventions for the ordering of bytes within multi-byte integers, known as ``big-endian'' (which stores the most significant byte first) and ``little-endian'' (which stores the least significant byte first). Which convention a particular machine uses depends on the vendor; for example DECs use little-endian, while SUNs use big-endian. This can result in problems when data sets are shared over the Internet. The UNIX utility dd can be used to convert between the two conventions --- this is called ``byte swapping.''

a property (internal data format) of a ROM