device-name

    Specifies a physical device name or a logical name equated to
    a physical device name. Specify the device name as a character
    string expression.

    After the device-name argument is evaluated, the F$MULTIPATH
    function examines the first character of the name. If the
    first character is an underscore (_), the name is considered a
    physical device name; otherwise, a single level of logical name
    translation is performed and the equivalence name, if any, is
    used.

 item

    Specifies the type of device information to be returned. The
    item argument must be specified as a character string expression.
    Currently, the only valid item is MP_PATHNAME, which returns a
    string with the path name for the specified multipath-capable
    device.

 context-symbol

    Prior to the first use of F$MULTIPATH with MP_PATHNAME, the
    context symbol must be initialized to a value of 0. The
    F$MULTIPATH function is responsible for maintaining the value
    of the context symbol.

                                 CAUTION

       Do not modify the context symbol value after it has been
       initialized to 0; doing so could result in unpredictable
       behavior of F$MULTIPATH.