Delphi Multi Units

unit mainUi;

interface

uses //Here we need to declare which units need to be accessed.
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, DBU,
  Dialogs, Menus, SpyArrayU, StdCtrls, ComCtrls, jpeg, ExtCtrls; 
  //make sure to include required units names.

type
procedure TFrmSpy.mmDisplayClick(Sender: TObject);
begin
  iSpyArray.Sort;  //Call sort procedure. //This procedure is in the SpyyArray Unit.
  Rchoutput.Lines.Add(iSpyArray.ToString)  //Call ToString Function.
end;   

unit SpyArrayU; //Please note this is an OOP unit, but principle remains the same.

interface

uses Sysutils, SpyU, DBU; //Further links to other objects/units.

  Type TSpyArray = Class
    Private
      SpyArr: Array[1..100] of spy; //Will require a Loop in most code.
      Size: Integer;
    protected

    Public
      Constructor create; //Always in Public.
      //Accessor Methods

      //Mutator Methods

      //Other Methods
      Procedure Sort;
      Function Search(which: string):string;
      Function ViewCoded: string;
      Function ToString: string;
  End;

  Var
    iSpyArray: TSpyArray;  //Declare object. Used to call object/unit. 

unit SpyArrayU; //Please note this is an OOP unit, but principle remains the same.

interface

uses Sysutils, SpyU, MainUI, DBU; //You can not declare the accessing unit from the source unit.

  Type TSpyArray = Class
    Private
      SpyArr: Array[1..100] of spy; //Will require a Loop in most code.
      Size: Integer;
    protected

    Public
      Constructor create; //Always in Public.
      //Accessor Methods

      //Mutator Methods

      //Other Methods
      Procedure Sort;
      Function Search(which: string):string;
      Function ViewCoded: string;
      Function ToString: string;
  End;

  Var
    iSpyArray: TSpyArray;  //Declare object/ unit. Used to call object/unit.

implementation

{ TSpyArray }
uses MenuUI; //Thus to avoid the error simply place a new uses under implementation.