The BK is entered in 'normal' order or as read, the IRD may or may not be entered normally, ie 12 ** ** ** or 3E ** ** ** or hex reversed ie 12 3a 4e 1f would become 1f 4e 3a 12...the pair order stays the same but the pairs are reversed...pair '12' retains its numerical order but moves position within the IRD, the IRD order depends on the software used to create the ext eep.
Quite a mouthful but hope this helps.
Muskrat