This document specifies common fundamental concepts for long term archiving and retrieval of mechanical CAD information for elementary parts and assemblies. It details the “fundamentals and concepts” of EN 9300-003:2012 in the specific context of long-term archiving of CAD mechanical models. Mechanical CAD information is divided into assembly structure and geometrical information, both including explicit and implicit geometrical representation, geometric dimensioning and tolerancing with form features. The EN 9300-1XX family is organized as a sequence of parts, each building on the previous ones in a consistent way, each adding a level of complexity in the CAD data model. This includes the detailing of relationships between the essential information for the different types of CAD information covered by the EN 9300-1XX family. As technology matures, additional parts will be released in order to support new requirements within the aerospace community.