La unidad que lo soporta es la
QControls 
Código Delphi
[-]Originalmente de Delphi Help
TModalResult represents the return value from a modal dialog.
Unit
QForms
Delphi syntax:
type TModalResult = Low(Integer)..High(Integer);
Description
TModalResult represents the value returned by a modal dialog. An application can use any
integer value as a modal result value. For convenience, the QControls
unit defines a set of constants for commonly used TModalResult values:
En fin, gracias de todos modos por la ayuda prestada
Salvica