WebPartCollection.Item Property (String)
Returns a member of the collection based on a unique string identifier.
Assembly: System.Web (in System.Web.dll)
The Web Parts control set performs case-insensitive matching on this property, so case sensitivity is not part of a unique id value.
The Item property also works to identify members of a WebPartCollection object in some specialized cases. In the case of GenericWebPart controls, the indexer is able to match the identifier for the underlying child control wrapped by the GenericWebPart control. In the case of ProxyWebPart controls, the indexer matches the identifier for the control based on a case-insensitive comparison of the id parameter and either the OriginalID or GenericWebPartID property values.