Decomposition of Four Component Items

Items are introduced as a universal formalism for describing data (ie individual things), information (ie relations) and knowledge (ie rules). A single rule for the normalisation of items is defined. The five normal forms for relational database together with the Boyce-Codd normal form provide a complete characterisation of the normalisation of 3-adic information items. New normal forms may be derived by applying our single rule of normalisation to n-adic items for n>3.