I just saw the reference to TIFF and byte order (something I dealt with extensively in a previous job).

TIFF files can be written in either big or little endian format, and its up to the reader to recognize the byte order and do the right thing. For writing out a new TIFF, you can choose either format provided that you write the entire TIFF. If you were trying to update an existing TIFF, then you need to respect the byte order.

TIFF files from Macs were traditionally big-endian (this was pre-MacOSX). I believe that tools like PhotoShop allow you to write either endian.

If we're writing our own JS to parse information from the TIFF, then we'd need to do the endian stuff. If we're using a C library (like libtiff) then it will take care of that automagically.