 One standardization is through what is known as  Common Logic  (CL), and variants thereof. (CL is published as an  ISO standard  – ISO is the International Standards Organization.) Philosophers interested in logic, and of course logicians, will find CL to be quite fascinating. From an historical perspective, the advent of CL is interesting in no small part because the person spearheading it is none other than Pat Hayes, the same Hayes who, as we have seen, worked with McCarthy to establish logicist AI in the 1960s. Though Hayes was not at the original 1956 Dartmouth conference, he certainly must be regarded as one of the founders of contemporary AI.) One of the interesting things about CL, at least as we see it, is that it signifies a trend toward the marriage of logics, and programming languages and environments. Another system that is a logic/programming hybrid is  Athena,  which can be used as a programming language, and is at the same time a form of MSL. Athena is based on formal systems known as denotational proof languages (Arkoudas 2000). 