The Format Date and/or Time routine allows the user to select
    at run time a specific output language and format for a date or
    time, or both.

    Format

      LIB$FORMAT_DATE_TIME  date-string [,date] [,user-context]

                            [,date-length] [,flags]

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 date-string

    OpenVMS usage:char_string
    type:         character string
    access:       write only
    mechanism:    by descriptor

    Receives the requested date or time, or both, that has been
    formatted for output according to the currently selected format
    and language. The date-string argument is the address of a
    descriptor pointing to this string.

 date

    OpenVMS usage:date_time
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference

    The date or time, or both, to be formatted for output. The date
    argument is the address of an unsigned quadword that contains
    the absolute date or time, or both to be formatted. If you omit
    this argument, or if you supply a zero passed by value, then the
    current system time is used. Note that the date argument must
    represent an absolute time, not a delta time.

 user-context

    OpenVMS usage:context
    type:         longword (unsigned)
    access:       modify
    mechanism:    by reference

    User context that retains the translation context over multiple
    calls to this routine. The user-context argument is the address
    of an unsigned longword that contains this context. The initial
    value of the context variable must be zero. Thereafter, the user
    program must not write to the cell.

    The user-context parameter is optional. However, if a context
    cell is not passed, the routine LIB$FORMAT_DATE_TIME may abort
    if two threads of execution attempt to manipulate the context
    area concurrently. Therefore, when calling this routine in
    situations where reentrancy might occur, such as from AST level,
    VSI recommends that users specify a different context cell for
    each calling thread.

 date-length

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       write only
    mechanism:    by reference

    Number of bytes of text written to the  date-string argument.
    The date-length argument is the address of a signed longword that
    receives this string length. Note that date-length specifies the
    number of bytes of text, not the number of characters, written to
    date-string.

 flags

    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Bit mask that allows the user to specify whether the date, time,
    or both are output. The flags argument is the address of an
    unsigned bit mask containing the specified values. Valid values
    are LIB$M_DATE_FIELDS and LIB$M_TIME_FIELDS.

    Default values are determined as follows:

    o  If the flags argument is omitted, LIB$FORMAT_DATE_TIME
       determines which fields to format according to the current
       definition of LIB$DT_FORMAT.

    o  If the flags argument is specified, LIB$FORMAT_DATE_TIME uses
       the flags value to determine which fields to format. That is,
       the flags argument can be used to override the definition of
       LIB$DT_FORMAT when specifying which fields should be formatted
       for output. If the field specified by flags was not assigned a
       format through the definition of LIB$DT_FORMAT, the standard
       OpenVMS format is used.