eader to judge. It is unavoidable that many abbreviations appear in a book like this. Most of these belong to the telecom domain. I have tried to repeat the interpretation of abbreviations frequently in the text, in order to ease the burden on the part of the reader. For most readers, the book introduces many new concepts. Concepts that have a formal definition in AML are rendered in italic, normally the first time they appear in the text, and then every time some aspect of the concept is discussed. Sysnet modelling and AML have evolved over almost twenty years. All the influences that have advanced the concept during these years I have received from somewhere or somebody else. It is therefore a pleasure to give recognition to my colleagues at Ericsson who have contributed over the years. Taken chronologically, without the challenge that Gösta Linder's remark meant to me twenty year ago, I would probably never have entered this track. I also feel deeply grateful to my late friend Oleg de Bachtin, who inspired me, taught me and believed in me at a time when I was more enthusiastic than competent. Lennart Holm probably contributed the most to the advancement of AML. Although he drove me almost to despair from time to time by questioning my every idea, without his engagement in AML, Preface it would not have reached the degree of maturity it has today. Others who put a lot of effort and enthusiasm into the development of AML during the same time period were Lars-Eric Ek, Öjvind Johansson and Bo Kronkvist. Thank you, guys. Without access to colleagues who have an interest in system modelling, it would have been impossible to develop this concept. I am very grateful for all the encour- agement and fruitful discussions I had over the years with the following colleagues: Abderrahman Ait Kaci Ali, Svante Asplund, Joseph el Batal, Michel Dubien, Con- rad Gagnon, Dominikus Herzberg, Jens Larsen, Francis Lupien, Urban Löfgren, Per-Arne Mannby, Olof Nasiell, Anders Olsson, Mats Olstedt, Stefan Sandh, Fran- cois Saywer, Akila