Levels of grammatical complexity constitute a basic structuring principle of a semasiological grammar. For each category of grammatical units (nominal, verbal, adverbial etc.), the progression is from the lowest (root) to the highest (syntagma, possibly clause) complexity level. The level hierarchy is the following:

Some of these levels may be split up for certain categories. For instance, for verbal constructions, it may be necessary to subdivide the syntagma level into verbal complex and verb phrase.

For each of the levels, the operations producing units of that level are described. For instance, in the chapter on the verb stem, verbal compounding, derivation of verb stems and conversion into a verb stem are described.

In the simplest case, morphological processes implementing a certain operation operate just on units of one level – the immediately inferior or the same level of the target of the operation. However, this is not always so. For an inflectional operation in particular, there may be allomorphy involving morphological processes applying at different complexity levels. For instance, a certain conjugation category like past tense may generally be coded by a suffix on the verb stem but may be coded by apophony if the verb stem is a mere root, as in English spell - spelled, but tell - told.

Generally, complexity levels and grammatical operations are paired as follows:

The problem for a semasiological grammar is then the proper locus of morphological operations which form the same (value of a) grammatical category but differ in their structural properties. Either the grammatical category in question or the structural properties of the morphological process in question constitute a relatively higher-ranging ordering principle in the grammar. Depending on this alternative, we get two competing subdivisions of the semasiological description:

1. If it is the grammatical category, there will be a section on the formation of the past tense; and it will have subsections for its formation on certain root verbs and its formation on verbs stems in general.
2. If it is the structural properties of the morphological process, there will be a section on processes that modify verb roots and a section on processes which modify verb stems. Both would include a subsection on the formation of the past tense.