Abstract: Methods and data structures which permit information to be stored as objects in target containers and update containers. A target container defines a first state of the information, and the update container, which can point to the target container, identifies changes to the information in the first state which would be sufficient to update the first information state to a second information state. Update containers may be nested to any depth. When an application program opens an update container, the procedure searches down the chain until it finds the ultimate target container. It then creates in-memory structures for providing access to the objects and value data represented in such container. The procedure then works its way back up the chain, performing the changes on the in-memory structure, which are called for in each of the update containers.

Abstract: Computer apparatus stores a subject value and a chain of sequentially associated value handlers for the subject value. The chain includes a top value handler and a bottom value handler, each of the value handlers in the chain except the bottom value handler invoking the respective next value handler when invoked, the bottom value handler performing an operation on the subject value when invoked. The value operations can be data read operations, data write operations, etc., and the value handlers in the chain can perform data transformations and/or data redirections, transparently to its caller.