I was invited to speak about TLA at the FMCO symposium. I didn’t feel that I had anything new to say, so I asked Brannon Batson who was then at Intel to help me prepare the talk and the paper. Brannon is a hardware designer who started using TLA+ while at Compaq and has continued using it at Intel. The most interesting part of this paper is Section 4, which is mainly devoted to Brannon’s description of how his group is using TLA+ in their design process. Section 5 was inspired by the symposium’s call for papers, whose list of topics included such fashionable buzzwords as “object-oriented”, “component-based”, and “information hiding”. It explains why those concepts are either irrelevant to or are a bad idea for high-level specification.