Codd produced 12rules as part of a personal campaign to prevent the vision of the original relational database from being diluted, as database vendors scrambled in the early 1980s to repackage existing products with a relational veneer. Rule 12 was particularly designed to counter such a positioning. Even if such repackaged non-relational products eventually gave way to SQL DBMSs, no popular relational DBMSs could be considered relational, be it by Codd's twelve rules or by the more formal definitions in his papers and books. Only less known DBMSs ├?┬ó?? most of them restricted to academic usage ├?┬ó?? strive to comply. The only commercial example, as of December 2010, is Dataphor. Some rules are deemed controversial, especially rule 3, because of debate on three-valued logic.