Functional varieties of language are defined as bundles of linguistic features ('registers') the occurrence of which is determined by non-linguistic factors ('utterance constellations'). The central concept that S. handles on the level of 'utterance constellations' is the relationship between speaker and hearer (which can be ceremonial, formal politeness, obligation, free collaboration, goodwill, friendship, confidence). Each of those seven types of relationship corresponds with a register. A further description of those registers is given in terms of their morphological, lexical, syntactic and pragmatic features. (On the pragmatic level S. borrows notions from speech act theory.)