Int 31 Fn FF23  P - Causeway - "relmemdos" - Release Conventional Memory   [E]

   AX = FF23h
   DX = initial selector for block

Return: CF clear if successful
   CF set on error
       AX = DOS error code (see #1366 at INT 21/AH=59h/BX=0000h)

Note:  all descriptors allocated for the block are freed

See Also: AX=FF21h,AX=FF22h,INT 21/AH=4Ah