The basic idea for the present purpose is that there is a set of descriptive parameters according to which functionally equivalent constructions may be ordered, and that these parameters correlate, i.e. tend to effect the same order among such constructions, and that they are all aspects of a more general phenomenon called grammaticalization.

Lehmann 1982 proposes a system of six parameters to assess a given case of grammaticalization or the degree to which a given construction or formative is grammaticalized. These six parameters of grammaticalization may be arranged, according to the selective and combinatory aspect of every linguistic operation (cf. Jakobson 1956), in a paradigmatic and a syntagmatic group, and according to the aspect of the autonomy of the language sign, in three binary groups.

Each cell of the classification shows first the parameter, which is a kind of property, then the associated process, which is dynamic. The general denominators of the two columns of this schema are the following: With increasing grammaticalization, both the paradigm and the syntagma are consolidated.

The six parameters spell this generalization out. Most attention will be devoted to eligibility and obligatorification as these are probably the most crucial aspect of grammaticalization. Desemanticization and erosion will be treated last for two reasons: First, they only affect the individual lexical item or grammatical formative and have little to do with its paradigmatic and syntagmatic relations. Second, they affect grammaticalized items in the same way as they affect lexical items. For these two reasons, they have a subordinate status in the set of parameters of grammaticalization.