Format of VBE/AF BitBlt parameter block:
Offset	Size	Description	)
 00h	WORD	left coordinate of source rectangle
 02h	WORD	top coordinate of source rectangle
 04h	WORD	right coordinate of source rectangle
 06h	WORD	bottom coordinate of source rectangle
 08h	WORD	left coordinate of destination rectangle
 0Ah	WORD	top coordinate of destination rectangle
 0Ch	BYTE	horizontal direction: 00h = decrement X, 01h = increment X
 0Dh	BYTE	vertical direction: 00h = decrement Y, 01h = increment Y
Notes:	the rightmost pixel(s) and bottom-most scan line are not copied
	the horizontal/vertical direction flags are used to ensure correct
	  copies when the source and destination rectangles overlap
SeeAlso: #00099