Although software agents were not part of the original KSE vocabulary the conceptual break-down of the "common language problem" was quickly recognized as applicable to the multiagent systems paradigm. Expressions in a given agent's native language should be understood by some other agent that uses a different implementation language and domain assumptions. So, the first layer is that of (syntactic) translation between languages in the same family (or between families) of languages. Another layer is concerned with guaranteeing that the semantic content of tokens is preserved among applications; in other words, the same concept, object, or entity has a uniform meaning across applications even if different "names" are used to refer to it. Every agent incorporates some view of the domain (and the domain knowledge) it applies to. The technical term for this body of "background" knowledge is ontology.
A final layer addresses the communication between agents. This is not about transporting bits and bytes between agents; agents should be able to communicate complex "attitudes" about their information and knowledge content. Agents need to ask other agents, to inform them, to request their services for a task, to find other agents who can assist them, to monitor values and objects, and so on. Such functionality, in an open environment, can not be provided by a simple Remote Procedure Call (RPC) mechanism. Agents issue requests by specifying not a procedure but a desired state in a declarative language, i.e., in some Agent Communication Language. The KSE developed KQML, the Knowledge Quey and Manipulation Language, as a standard for peer to peer communication.
Within the KSE, these layers were viewed as independent of another. The ACL is only concerned with capturing propositional attitudes, regardless of how propositions are expressed. But still, propositions are what agents will be "talking" about. KIF, a particular logic language, was proposed within the KSE as a standard to use to describe things within computer systems, e.g., expert systems, databases, intelligent agents, etc. Moreover, it was specifically designed, within the context of the KSE, to make it useful as an interlingua. KIF is a prefix version of first order predicate calculus with extensions to support non-monotonic reasoning and definitions. The language description includes both a specification for its syntax and one for its semantics. Ontolingua and a variety of supporting tools, was the KSE "solution" to the problem of developing and maintaining ontologies. Researchers at Stanford's Knowledge Systems Laboratory developed a set of tools and services to support the process of achieving consensus on common shared ontologies by geographically distributed groups. These tools were built around Ontolingua, a language designed for describing ontologies with it, and make use of the world-wide web to enable wide access and provide users with the ability to publish, browse, create, and edit ontologies stored on an ontology server.