Allows installations to provide their own routine to interpret
    and output the accessibility field in the VOL1 and HDR1 labels of
    an ANSI labeled magnetic tape.

    Format

      SYS$MTACCESS  lblnam ,[uic] ,[std_version] ,[access_char]

                    ,[access_spec] ,type

    C Prototype

      int sys$mtaccess  (unsigned int *lblnam, unsigned int uic,

                        unsigned int std_version, unsigned int

                        access_char, unsigned int access_spec,

                        unsigned int type);

1  –  Arguments

 lblnam

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    ANSI label to be processed. The lblnam argument is the address
    of a longword containing the label. On input, the label passed
    is either the VOL1 or HDR1 label read from the magnetic tape; on
    output of labels, the value of this field is 0. The type of label
    passed is determined by type.

 uic

    OpenVMS usage:uic
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    UIC of the user performing the operation. The uic argument is a
    longword containing the UIC.

 std_version

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Decimal equivalent of the ANSI standard version read from the
    VOL1 label. The std_version argument is a longword containing the
    standard version number.

 access_char

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Accessibility character specified by the user. The access_char
    argument is a byte containing the accessibility character used
    for the output of labels.

 access_spec

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Value specifying whether the accessibility character passed in
    access_char was specified by the user.

    The access_spec argument is a byte containing one of the
    following values:

    Value            Meaning

    MTA$K_           Yes
    CHARVALID
    MTA$K_NOCHAR     No

    This argument is used only for the output of labels.

 type

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Type of accessibility field to process.

    The type argument is a byte containing one of the following
    values:

    Value            Meaning

    MTA$K_INVOL1     Input a VOL1 label
    MTA$K_INHDR1     Input a HDR1 label
    MTA$K_OUTVOL1    Output a VOL1 label
    MTA$K_OUTHDR1    Output a HDR1 label