A revised and expanded publication for suppliers and users of radiation hardness assured (RHA) multichip modules (MCMs) and hybrid microcircuits, is now available. Revision A of JEP133 includes modifications to the introduction, clarification of a definition and clarification of several technical issues within the document. In addition, the Bibliography section was updated to include added references. The document provides guidance as to how to achieve, maintain and ensure required levels of radiation-hardness given the fact that the constituent dice can have different levels of hardness assurance. It also describes how to deal with the various radiation hardness situations that an MCM/Hybrid developer, procuring activity or user will encounter. The guide is intended to supplement three relevant performance specifications: MIL-PRF-38534, MIL-PRF-38535 and MIL-PRF-19500.