In (66) all three members of sort of thing are ditto-tagged as a 'formulaic expression' (FRM) functioning as a discourse marker: Clearly sort of is a nightmare for tagging. 2.5 Case study 5: P ~ infinitive marker ~ M In ANC2, to as infinitive marker has a tag of its own, TO (both Penn and Biber tagsets), likewise BNC (TO0) and DCPSE (TO): it is in effect what Pullum (1982) calls "syncategoremic.