Dataphor is an open-source truly-relational database management system (RDBMS) and its accompanying user interface technologies, which together are designed to provide highly declarative software application development. The Dataphor Server has its own storage engine or it can be a virtual, or federated, DBMS, meaning that it can utilize other database engines for storage. Dataphor has been praised for its adherence to relational principles, more closely so than any SQL product. Overview The stated purpose of Dataphor is to attempt to raise the bar of automation when building and maintaining complex software applications. Originally referred to as a framework, Dataphor provides more of a software development platform, complete with its own programming and user interface paradigms. Dataphor is broadly divided into two components: the Dataphor Server, and the Dataphor Frontend. The purpose of the Dataphor Server is to provide a standardized language and runtime for the definition, manipulation, and integrity of application data. The Frontend is concerned with the dynamic derivation of user interfaces and the presentation thereof in either the Windows or Web thin client. Dataphor does not employ SQL as its primary database language since SQL purportedly violates important principles of the relational model. Dataphor's D4 language is based on the principles of Christopher J Date's and Hugh Darwen's Tutorial D, but with a Pascal-like imperative syntax. Though Dataphor espouses to be truly relational, it does incorporate the concept of NULLs as found in SQL, which many claim to be contraindicated by the Relational Model. NULLs and the matter of managing missing information, however, continue to be debated. In addition to the data management focus of the Dataphor Server, Dataphor includes tools which allow the presentation of user interfaces through Windows and Web "thin" clients. Dataphor takes advantage of the relational inference capabilities of the Dataphor compiler in order to allow complete GUI forms to be derived directly from the data model. The unique aspect of Dataphor's user interface "derivation" is that it may be based on any relational expression (query) rather than merely base tables. Truly relational Dataphor strives for theoretical compliance to relational principles. While they try to adhere to the principles in The Third Manifesto, they deviated in a few places from what the Third Manifesto strived for, but not in places that were violations of Codd's 12 rules. E.g. they included nulls, but they claim to have a systematic treatment of them. While many systems