The EN 4660 standard series has been prepared on the basis of the second phase of the ASAAC Programme (ASAAC Phase II Contract). The ASAAC is the Allied Standard Avionics Architecture Council which was founded with the aim to develop basics of modern avionics architecture. The purpose of the ASAAC Programme is to define and validate a set of open architecture standards, concepts and guidelines for Advanced Avionics Architectures (A3) in order to meet the three main drivers for the programme. The standards, concepts and guidelines produced by the Programme are to be applicable to both new aircraft and update programmes. The three main drivers for the ASAAC Programme are: - reduced life cycle costs; - improved mission performance; - improved operational performance. The standards are organised as a set of documents including: - a set of agreed standards that describe, using a top down approach, the architecture overview to all interfaces required to implement the core within avionics systems; - the guidelines for system implementation through application of the standards. The purpose of Part 004 of EN 4660 is to establish uniform requirements for Packaging for the Common Functional Modules (CFM) within an Integrated Modular Avionic (IMA) system, as defined per ASAAC. This document comprises the module physical properties and the Module Physical Interface (MPI) definitions together with guidelines for IMA rack and the operational environment. The characteristics addressed by the Packaging Standard are: Interchangeability: - For a given cooling method all modules conforming to the packaging standard will function correctly when inserted into any rack slot conforming to the standard for the cooling method; - All modules conforming to the MPI definitions for connector, IED and cooling interface will function correctly when inserted into any rack slot conforming to the same MPI definition. Maintainability: - All modules are easily removable at first line; - No special tools required at first line; - No manual adjustment is necessary when installing modules. No tool is required for installation or removal of the modules; - Mechanical keying is provided that prevents insertion of a module into a rack slot that may cause an unsafe condition. The Module Physical Interface definition, contained within this standard, does not include the properties of the signalling used in the optical interface (for example, wavelength). These are covered in EN 4660-003. This standard EN 4660-004:2011 has been prepared by ASD-STAN, Technical Section Electrics, Avionics, with the participation of German experts of the Aerospace Standards Committee. The European Committee for Standardization (CEN) declared the Aerospace and Defence Industries Association of Europe (ASD-STAN) responsible for the preparation of European standards (EN) for the field of aerospace. ASD became the associated body (ASB) of CEN by the agreement dated 1986-10-03. The responsible German standardization committee is Working Committee NA 131-04-09 AA "Avionik" ("Avionics") of the Aerospace Standards Committee at DIN.