See Also: SiteMapNodeCollection Members
You can create a read-only System.Web.SiteMapNodeCollection, which does not permit adding, copying, nor removing System.Web.SiteMapNode objects, by using the static SiteMapNodeCollection.ReadOnly(SiteMapNodeCollection) method. The System.Web.SiteMapNodeCollection collections that are returned by the SiteMapNode.GetAllNodes and System.Web.UI.IHierarchyData.GetChildren methods are read-only, as is the System.Web.SiteMapNodeCollection that is returned when the SiteMapNode.ChildNodes property is accessed on a System.Web.SiteMapNode object that is returned from a provider. A NotSupportedException exception is thrown, if you attempt to modify a read-only System.Web.SiteMapNodeCollection by setting the default indexer property or by using any of the following methods:
Use the SiteMapNodeCollection.IsReadOnly property to check the collection before calling any of the methods in the preceding list.