status of the conversation for action need not be concerned with modeling all of the realities of the external world. A conversation for action is critically dependent upon certain stereotypical claims about the status of the world made by the two parties. Thus a conversation for action can be readily tracked and facilitated by a device with little or no ability to model circumstances in the real world other than the ability to register claims by specific agents about a domain. Rules In the past, philosophy has discussed rules for when expressions are used. The two rules are constitutive and regulative rules. The concept of constitutive rules finds its origin in Wittgenstein and John Rawls, and has been elaborated by G.C.J. Midgley, Max Black, G.H. von Wright, David Shwayder, and John Searle. Whereas regulative rules are prescriptions that regulate a pre-existing activity (whose existence is logically independent of the rules), constitutive rules constitute an activity the existence of which is logically dependent on the rules. For example: traffic rules are regulative rules that prescribe certain behaviour in order to regulate the traffic. Without these rules however, the traffic would not cease to be. In contrast: the rules of chess are constitutive rules that constitute the game. Without these rules chess would not exist, since the game is logically dependent on the rules. In multiagent universes Multi-agent systems sometimes use speech act labels to express the intent of an agent when it sends a message to another agent. For example, the intent "inform" in the message "inform(content)" may be interpreted as a request that the receiving agent adds the item "content" to its knowledge-base; this is in contrast to the message "query(content)" which may be interpreted (depending on the semantics employed) as a request to see if the item content is currently in the receiving agents knowledge base. There are at least two standardisations of speech act labelled messaging KQML and FIPA. KQML and FIPA are based on the Searlian, that is, psychological semantics of speech acts. Munindar P. Singh has long advocated moving away from the psychological to a social semantics of speech acts—one that would be in tune with Austin's conception. Andrew Jones has also been a critic of the psychological conception. A recent collection of manifestos by researchers in agent communication reflects a growing recognition in the multiagent systems community of the benefits of a social semantics. Other