Compatibility: XMS 2.0+
Expects: AH    0dH
DX    XMS handle (as obtained via XMS 09H)
                                                                  
Returns: AX    status: 0000H = successful
0001H = error and BL=XMS error code (if BL >= 80H)
DX:BX 32-bit linear address of base of block
                                                                  
Info: This unlocks an extended memory block that has been locked via
XMS 0cH.  After unlocking, any 32-bit pointers to the data become
invalid.

XMBs should be unlocked as soon as possible to avoid memory
fragmentation.

The XMM maintains a "lock-count" and only allows the block to
move when the lock count is decremented to 0.  XMS 0eH obtains
the current lock count.

See Also: XMS Functions
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XMS 0dH: Unlock Extended Memory Block