We address the problem of standardising the semantics of agent communication. The diversity of existing approaches suggests that no single agent communication language can satisfactorily cater for all scenarios. However, standardising the way in which different languages are specified is a viable alternative. We describe a standard meta-language in which the rules of an arbitrary institution can be specified. In this way different agent communication languages can be given a common grounding. From this starting point, we describe a component based approach to standardisation, whereby a standard can develop by adding component sets of rules; for example to handle various classes of dialogs and normative relations. This approach is illustrated by example. Eventually we envisage different agent institutions publishing a specification of their rules by simply specifying the subset of standard components in use in that institution. Agents implementing the meta-language can then interoperate between institutions by downloading appropriate components.