DEFINITION MODULE StdIO;
  (* Access to standard and default files *)

IMPORT File;

PROCEDURE StdInFile (): File;
  (* Returns the identity of the implementation-defined standard source for program input. *)
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PROCEDURE StdOutFile (): File;
  (* Returns the identity of the implementation-defined standard source for program output. *)

PROCEDURE StdErrFile (): File;
  (* Returns the identity of the implementation-defined standard destination for program
      error messages. *)

PROCEDURE NullFile (): File;
  (* Returns the identity of a channel open to the null device. *)

  (* The following functions return the default channel values *)

PROCEDURE InFile (): File;
  (* Returns the identity of the current default input channel. *)

PROCEDURE OutFile (): File;
  (* Returns the identity of the current default output channel. *)

PROCEDURE ErrFile (): File;
  (* Returns the identity of the current default error message channel. *)

  (* The following procedures allow for redirection of the default files *)

PROCEDURE SetInFile (fid: File);
  (* Sets the current default input channel to that identified by fid. *)

PROCEDURE SetOutFile (fid: File);
  (* Sets the current default output channel to that identified by fid. *)

PROCEDURE SetErrFile (fid: File);

  (* Sets the current default error channel to that identified by fid. *)

END StdIO.