INT 16 - Swap Utilities - ???
        AX = 55FFh
        BX >= 0004h
        CX = function
            0000h set ??? flag
            other clear ??? flag
Note:   present in SWAPSH and SWAPDT v1.77j, distributed with PC Tools v7, as
          well as the Trusted Access SCRNBLNK.COM; this may be part of the
          standard TesSeRact library
SeeAlso: INT 2F/AX=5453h

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