This paper introduces some major conceptual enhancements to the morphological annotation of the SYN series corpora of the Czech National Corpus. Apart from minor changes in tokenization and in the positional tagset, three major conceptual changes have been applied which affect the representation of various lexical and grammatical patterns. In the paper, we present the actual impact of the changes in linguistic data and search for possibilities in three linguistic areas. First, the treatment of phonic, graphemic, and morphological variants via a two-tier lemma structure is discussed; second, a new approach to periphrastic verb forms, auxiliaries, participles and the interpretation of verbal grammatical categories through a new attribute, called verbtag, is explained; and third, a complex multi-value treatment of multiword tokens is introduced.