|-
| 1
| 0Drive Definition Byte
|-
| 1
|}
The drive definition byte is as follows: {| border="1"|-! Bit ! Description|-| 3 | Double-stepped if set|-| 2| Head when not double-sided|-| 1 | Unused|-| 0| Double-sided when set|} If the image is double-sided, alternate heads are stored for each cylinder. ARC files written by older versions of Xexor have the following header(ie. XA missing):
{| border="1"