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  Arguments
 
    file_variable    Optional; text file (default is standard file
                     Input)
 
    <expression>     Optional; expression of any simple type
 
    <format>         Optional; depends on type of expression
 
  Description
 
    The Writeln procedure writes zero or more values followed by an
    end-of-line (carriage-return and line-feed) to a disk file or
    device. Writeln always appends to a file. The current position is
    always at end-of-file.
 
    The file must be a text file, opened for output with the Append or
    Rewrite procedure. If no output file is specified, Writeln writes
    to the standard text file Output. Standard output goes to the screen
    unless redirected to a file by the DOS redirection operator, (>).
    Use the Assign procedure to reenable redirection when using the Crt
    unit.
 
    If Writeln is called with no expressions, it writes an end-of-line
    to the file. On the screen, it moves the cursor to the first column
    on the next line.
 
    The format argument is optional and varies with the expression
    type:
 
      1. For character, Boolean, or string output, the format is
 
           <expression> [ : width ]
 
         The width argument is a positive integer expression giving a
         minimum field width. The characters are right justified within
         the field if they fit. If they do not fit or if width is
         omitted, the characters take as much space as needed.
 
         For Boolean expressions, the output is a string of text,
         either 'TRUE' or 'FALSE'.
 
      2. For numeric output the format is
 
           <expression> [ : width [ : places ] ]
 
         The width and places arguments are positive integer
         expressions that control the conversion format. The
         expression is either an integer or a real type. The
         formatting specification is the same as that passed to
         the Str procedure.
 
         The width argument gives the minimum field width. The number
         is right justified within the field if it fits. For an
         integer, if the number does not fit or if width is omitted,
         the number takes as much space as needed. For a real number,
         if width is less than 8, the value is ignored and a field
         width of 8 is used. If width is omitted, a width of 23 is
         assumed. The field width includes the decimal point and any
         places after the decimal. A negative width is ignored.
 
         The places argument gives the number of places to the right of
         the decimal. This parameter applies only to real arguments
         when width is specified. If places is greater than 18 or is
         negative, 18 decimal places are used. Omit places or give a
         negative value to write in scientific (engineering) notation.
         Specify 0 places to round a real to the nearest whole number.
 
    The output string for an integer has the form:
 
       [-] <decimal digits>
 
    The output string for a real number has the form:
 
       [-] <digits> [.<digits>] [ {E│e} [+│-] <digits> ]
 
    Numeric output in hexadecimal format is not possible.
 
    If file_variable is not associated with a file or if the file is
    not open when Writeln is called, an I/O error occurs.
 
    If Writeln is called for a file opened for reading with Reset, an
    I/O error occurs.
 
    To prevent a program from halting with a run-time error when an I/O
    error occurs, turn off I/O checking with {$I-} and check the return
    value of the IOResult function.