[en] The PETRA electron-positron collider at DESY in Hamburg, Federal Republic of Germany, began operating in 1978, with four intersection regions devoted to experiments. In the intervening five years, five detector devices, CELLO, JADE, MARK-J, PLUTO and TASSO have accumulated and published a substantial variety of experimental results. The limits of validity of Quantum Electro-Dynamics (QED) have been extended; the pointlike nature of leptons and quarks have been probed at exceedingly small distances; the Glashow, Weinberg and Salam (GWS) '' standard electroweak model'' has been tested and found to describe interactions remarkably well; the predicted interference between electromagnetic and weak forces has been conclusively demonstrated; events with three jets have been discovered and interpreted as resulting from gluons, as predicted by Quantum Chromo-Dynamics (QCD); the sixth, ''top,'' quark has not been found yet, although an energy search for ''toponium'' (top + antitop) has been carried out up to 43.1 GeV center of mass energy. An integrated luminosity of about 100 pb/sup /minus/1/ mostly at energies above 30 GeV, has produced a very large sample of events. The present paper is a complete review and up-dating of all MARK-J physics results either published or unpublished. Since the amount of interesting information is so large, we realized that a coherent summation could be of substantial usefulness to the community. In order that this review can serve many needs, we include, a brief description of the apparatus and the data acquisition and analysis