Abstract:
A data processing system creates a log of operations performed on data units within a data structure, such as on objects corresponding to cards and links in a hypermedia database. The log includes items, each with data indicating an operation and indicating the unique identifier (UID) of each object affected by the operation. In response to a user request, the system scans through the log and includes appropriate data in the object corresponding to a special card called the history card. The data included in the history card's object for an item in the log can include a description of the operation indicated in that item and data for providing access to an affected card through an icon that is presented in the history card. Data indicating the affected card's UID is also associated with the history card's object, either by being included in the object or by being included in a linking data unit or object associated with the history card's object and with the affected card's object. The icon can be a pointer icon that provides one-way access in which case the user can subsequently request that the pointer icon be converted to a link icon that provides two-way access; in response to such a request, the system creates a linking object accessible both from the history card's object and from the affected card's object.