You can mark a property with this attribute to indicate that its value can be modified only at design time. This indicates that no code will be generated when the user changes the property in the designer. Compare this with the ReadOnlyAttribute , which will prevent the designer from modifying the value. public sealed class DesignOnlyAttribute : Attribute { // Public Constructors public DesignOnlyAttribute (bool isDesignOnly ); // Public Static Fields public static readonly DesignOnlyAttribute Default ; // =System.ComponentModel.DesignOnlyAttribute public static readonly DesignOnlyAttribute No ; // =System.ComponentModel.DesignOnlyAttribute public static readonly DesignOnlyAttribute Yes ; // =System.ComponentModel.DesignOnlyAttribute // Public Instance Properties public bool IsDesignOnly {get; } // Public Instance Methods public override bool Equals (object obj ); // overrides Attribute public override int GetHashCode (); // overrides Attribute public override bool IsDefaultAttribute (); // overrides Attribute } HierarchySystem.Object System.Attribute DesignOnlyAttribute Valid OnAll |