/sys$common/syshlp/helplib.hlb Lexicals, F$FAO, Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 control-string

    Specifies the fixed text of the output string, consisting of
    text and any number of FAO directives. The control string may
    be any length. Specify the control string as a character string
    expression.

    The F$FAO function uses FAO directives to modify or insert ASCII
    data into the fixed text in the control string.

 argument[,...]

    Specifies from 1 to 15 arguments required by the FAO directives
    used in the control string. Specify the arguments as integer or
    character string expressions.

    FAO directives may require one or more arguments. The order
    of the arguments must correspond exactly with the order of the
    directives in the control string. In most cases, an error message
    is not displayed if you misplace an argument.

    If you specify an argument whose type (integer or string) does
    not match that of the corresponding directive, unpredictable
    results are returned. You can use the F$INTEGER and F$STRING
    lexical functions to convert arguments to the proper type.

    If there are not enough arguments listed, F$FAO continues reading
    past the end of an argument list. Therefore, always be sure to
    include enough arguments to satisfy the requirements of all the
    directives in a control string.

    If you specify an invalid parameter for any directive, you may
    see unexpected errors, which indicate that the command did not
    succeed. (These errors are passed through to you from the $FAO
    system service.)