The theoretical base for this reformulation is to be found in a branch of sociology called ethnomethodology. According to Suchman, plans are representations of situated actions that only occurs when otherwise transparent activity becomes in some way problematic. The objectivity of the situations of our action is achieved through the indexicality of language. By saying that language is indexical Suchman means that the meaning of its expressions is conditional on the situation of their use. At least the communicative significance is always dependent on the situation.
Language is a form of situated action.
The relation of language to particular situations parallels the relation of instructions to situated action. As a consequence of the indexicality of language, mutual intelligibility is achieved on each occasion of interaction with reference to situation particulars, rather than being established once and for all by a stable body of shared meanings. Instead of looking for a structure that is invariant across situations we should try to understand how we manage to interact in ever changing contextual settings and still interpret and understand meaning and rationality. The communicative resources used for this include turn taking, adjacent pairs and agendas. Adjacent pairs is an extension to turn taking that denotes e.g. recursively embedded follow-up questions.