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  Arguments
 
    file_variable    Open typed or untyped file
 
    index            Integer expression representing a position in
                     the file; must be nonnegative and in the range
                     of a LongInt
 
  Description
 
    The Seek procedure sets the current position within an open nontext
    file. The new position is at the beginning of the component located
    at a given index. The next file operation is performed at the new
    position.
 
    Seek allows random access (forward and backward movement) within
    nontext files. Typed or untyped files can be directly modified.
 
    Seek cannot be applied to text file variables. To move randomly
    within a text file, declare file_variable as FILE OF Char.
 
    Components are numbered from 0 through the positive integers. The
    last component has an index one less than the number of components
    in the file.
 
    To append to a nontext file, Seek to the end of the file. Use the
    FileSize function to find the current number of components in the
    file. Then Seek to one place beyond the last component, as in
 
       Seek( file_variable, FileSize( file_variable ) );
 
    Do not Seek beyond one past the current last index.
 
    To move relative to the current position in a file, use Seek with
    the FilePos function. Seek to the current position plus or minus
    the desired number of records. For example, to reread a record,
    back up one place:
 
       Seek( file_variable, FilePos( file_variable ) - 1 );
 
    If file_variable is not associated with a file or if the file is
    not open when Seek is called, 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.