Int 62 Fn 0021  u - Fgdriver V4.02 - "fg_drawrelx" - Xor Solid Line To Re  [V]

   AX = 0021h
   BX = endpoint column offset
   CX = endpoint row offset
Desc:  draw a solid line, XORing each pixel onto the screen

Notes: the FGDRIVER functions are rearranged with each major release, but
     their parameters do not change (see #3145 at AX=0000h)
   This call is ignored in text modes
   The starting point is the current graphics cursor position; the cursor
     position is updated

See Also: AX=0006h,AX=000Dh,AX=001Dh,AX=0020h,AX=0026h,AX=0090h