Int 2D  - Dtown Utilities V1.40+ - Memory View Set Reference               [U]

   AL = 51h
   BL = reference ("bookmark") number
   CX:DX = new address for reference

Return: AL = status
       00h invalid index
       FFh reference set

Note:  this function is only available if the extended API has been installed
     in the resident portion
Program: DTown Utilities is a shareware programmer's utility TSR by Jeroen van
     Disseldorp

See Also: INT 2D/AL=10h"DTown",INT 2D/AL=20h,INT 2D/AL=50h