Hence, the metrical structure of the genitive singular assumes a greater role in identifying class outside the first declension.
As in the first declension, the partitive singular can be taken to define the stem of the genitive plural, in which case the second declension genitive plural exponent is -e rather than -te.
The second declension is more prosodically heterogeneous than the first declension, though the prosodic variation does not correlate with class-defining inflectional patterns.
These stem partitives are based on the genitive singulars 'alguse, kusimuse and inimese, not on the partitive singulars, as in the first declension.
Prosodically, the third declension patterns with the first declension.
A genitive singular such as aku 'battery' does not identify class, given first declension forms such as elu 'life'.
Given that the variation in the form of nominative singulars is predictable from the prosodic structure of the partitive singular, there is no motivation for dividing the first declension into 'truncating' and 'nontruncating' subtypes.
A trisyllabic genitive singular that does not end in -us also belongs to the first declension, as illustrated by koridor or seminar 'seminar'.
The observation that genitive singulars of most first declension nouns have an even number of syllables while those of second declension nouns often have an odd number of syllables is sometimes taken as evidence that the partitive and genitive plural exhibit syllable-conditioned allomorphy.
The contrast between the first declension partitive singular and genitive plural forms 'lippu and 'lippude and the second declension counterparts 'aastat and 'aastate cannot be attributed to any prosodic difference between the stems 'lippu and 'aasta.