The Data Dictionary System is an I/O System (and much more) capable of handling multi-dimensional seismic datasets (up to 9 dimensions; eg. "axis= t offset shot x y") in various formats including usp (BP Amoco's Un*x Seismic Processing), segy (Society of Exploration Geophysicists SEG-Y format), segy1 (SEG's SEG-Y Rev 1.0 format), sep (Stanford Exploration Project's format), su (Colorado School of Mine's Seismic Un*x format) as well as other flexible trace definitions (with or without trace headers) such as fcube. DDS allows different processing systems to be used together by piping directly together as well as through actual emulation of different processing systems.
A DDS dataset normally consists of a Dictionary and Binary data. A DDS Dictionary is a text file consisting of free-form Definitions, each given by a Definition name, an equal symbol ("=") and a value which can be nearly anything without an "=" character. The command line can be used to override any Dictionary Definitions. Also, a "par" file containing command line definitions can be specified on the command line by par=filename.
The Dictionary defines the Binary data format and contains any accumulated processing history. The underlying data model for the Dictionary uses data structural syntax similar to the "C" programming language. The Binary data is normally in a separate file from the Dictionary and is pointed to by the Dictionary. The Binary can, however, be attached to the end of the Dictionary in order to keep the dataset contained in a single physical file. Specific formats like usp or segy are already predefined within DDS and can therefore exist as a single binary file without the need for a Dictionary in which case they default to 3D data with axis= t x y.
DDS also has multi-file support where multiple conformable files can be arbitrarily merged for processing by simply creating a master Dictionary file pointing to the various individual files. It has been used in production on many different systems including CM5, Cray, Sun, SGI, Linux, Lunix clusters (32 & 64 bit); and even tested on several others. It is currently used in production on large Terabyte datasets with MPI and OpenMP parallelization.
DDS is being offered in open source by BP America Inc under FreeDDS along with a small collection of seismic imaging programs and associated utilities.