This report provides an overview of changes and improvements to the Architecture Analysis & Design Language (AADL) standard for describing both the software architecture and the execution platform architectures of performance-critical, embedded, real-time systems. The standard was initially defined in the document SAE AS-5506 and published in November 2004 by SAE International (formerly the Society of Automotive Engineers). SAE International published the revised language, known as AADL V2, in January 2009. Feedback from users of the standard guided the plan for improvements. Their experience and suggestions resulted in the addition of component categories to better represent protocols as logical entities (virtual bus), scheduler hierarchies and logical time partitions (virtual processor), and a generic component (abstract). The revisions also led to the abilities to (1) explicitly parameterize component declarations to better express architecture patterns, (2) specify multiple instances of the same component in one declaration (component array) and corresponding connection patterns, (3) set visibility rules for packages and property sets that access other packages and property sets, (4) specify system-level mode transitions more precisely, and (5) use additional property capabilities including property value records.