Abstract: An apparatus for detecting errors in frames of seismic data that can be presented as images, such images being expected to exhibit an inherent symmetry about an axis, the apparatus comprising: a storage device for storing a frame of seismic data which can be presented as an image; a selection device for selecting an axis within the image as the axis of symmetry; a divider for dividing the data about the axis of symmetry to create first and second sets of data; and a comparison means for comparing the sets of data according to preselected matching criteria to determine, based on the degree of matching, whether the extent of mismatch in the frame of data is within a predetermined tolerance.

Abstract: Data base administrator (10) creates program communication blocks (11), and programmer (12) writes programs (13) using the program communication blocks (PCBs) to store data in bulk storage device (14). A user (15) not having data processing skills or experience is enabled by means of a utility to access data in bulk storage device (14) via the PCBs (11). The utility first reads the data base descriptions (DBDs) and PCB source statements and constructs a data directory, consolidating access paths into entry data bases which are displayed to the user (15) as a menu. The utility then evaluates all possible access paths that will satisfy a user query, weights them according to their efficiency, and selects the best.