Abstract: A document search system provides a user with a programming interface for dynamically specifying features of documents recorded in a corpus of documents. The programming interface operates at a high-level that is suitable for interactive user specification of layout components and structures of documents. In operation, a bitmap image of a document is analyzed by the document search system to identify layout objects such as text blocks or graphics. Subsequently, the document search system computes a set of attributes for each of the identified layout objects. The set of attributes which are identified are used to describe the layout structure of a page image of a document in terms of the spatial relations that layout objects have to frames of reference that are defined by other layout objects. After computing attributes for each layout object, a user can operate the programming interface to define unique document features.

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.