Archi Mate®, an Open Group Standard, is an open and independent modelling language for Enterprise Architecture that is supported by different tool vendors and consulting firms. Archi Mate provides instruments to enable enterprise architects to describe, analyze, and visualize the relationships among business domains in an unambiguous way. This book provides the official specification of Archi Mate 2.1 from The Open Group. Archi Mate 2.1 is a maintenance update to Archi Mate 2.0, addressing comments raised since the introduction of Archi Mate 2.0 in 2012.The Archi Mate 2.1 Standard supports modelling throughout the TOGAF® Architecture Development Method (ADM). The intended audience is threefold: • Enterprise Architecture practitioners, such as architects (e.g. application, information, process, infrastructure, and, obviously, enterprise architects), senior and operational management, project leaders, and anyone committed to work within the reference framework defined by the Enterprise Architecture. • Those who intend to implement Archi Mate in a software tool; they will find a complete and detailed description of the language in this book. • The academic community, on which we rely for amending and improving the language, based on state-of-the-art research results in the enterprise architecture field.