E> (PE) Groups of logically rElatEd fiElds which occur multiplE timEs within a group. PEriodic groups arE a non-Ef="modulE.php?namE=LExikon&filE=sEarch&Eid=1&quEry=rElational">rElational tEchniquE. An ExamplE of a PE would bE for storing thE history of a pErson' s namE changEs, whErE namE was kEpt in logically rElatEd fiElds such as surnamE, first namE and middlE namE - with thE pErson having changEd thEir namE morE than oncE. [Clarification?] (1995-10-30)