Seek procedure

  DECLARATION:  Seek(var F; n : LongInt);

      PURPOSE:  Moves the current position of a file pointer to a specific
                component.

         UNIT:  System

      REMARKS:  F may be any file of any type except Text.  n is an
                expression of LongInt-Type.  The current file position is
                moved to component number n, with the first component of
                the file being 0.  To expand the file, you may Seek one
                component past the last component; ie: Seek(F,FileSize(F))
                moves the current file position to the end of the file.