INT 62 u - FGDRIVER v3.03 - "FG_DRAWRELX" - XOR SOLID LINE TO RELATIVE POSITION
        AX = 001Fh
        BX = endpoint column offset
        CX = endpoint row offset
Desc:   draw a solid line, XORing each pixel onto the screen
Notes:  For FGDRIVER v1.10, this function was "FG_POINT" (see AX=0076h);
          "FG_DRAWRELX" did not exist yet
        This call is ignored in text modes
        The starting point is the current graphics cursor position; the cursor
          position is updated
SeeAlso: AX=0006h,AX=000Dh,AX=001Bh,AX=001Eh,AX=0024h,AX=0077h

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