Bitfields for HP EX-BIOS driver header attributes:
Bit(s)	Description	)
 15	this is a complete driver header
 14	"ATR_DEVCFG" reserved
 13	driver can be mapped with the parent vector at offset 0Ah
 12	driver can be mapped with the child vector at offset 0Ch
 11-9	driver type
	000 reserved vector
	001 free vector
	010 EX-BIOS service
	011 logical driver (mapped from parent to child)
	100 mappable driver (cannot be last in driver chain)
	101 mappable driver that is last in driver chain
	110 input driver (mappable)
	111 reserved
 8	"ATR_STRING" reserved
 7	call SF_START whenever driver is remapped
 6-5	addressing requirements
	00 no subaddresses required
	01 requires major address be stored at offset 0Eh
	10 requires minor address be stored at offset 0Fh
	11 required major,minor, and mid addresses (minor in low nybble of
	      offset 0Fh, mid address in high nybble of 0Fh)
 4	driver can be shared between several parent drivers
 3	driver can be shared between several child drivers
 2	this driver header is in ROM
 1	"ATR_YIELD" reserved
 0	reserved
SeeAlso: #03745,#03747