The specification of common standards for linguistic categories/structures is more serious and challenging. If a common standard implies the recognition of invariants across different languages or different descriptions of the same language, then the extent to which this is feasible depends on the extent to which such invariants are recognised by those already working in the field. This may be unproblematic in the case of the grossest categories such as Noun, Prepositional Phrase, etc., but as one moves toward (a) greater granularity of description, and (b) more abstract levels of linguistic annotation, the degree of consensus is likely to decline. The level of morphosyntactic tagging is the one most favourable to a reasonable degree of standardisation in this sense and is also the level for which the urgency of establishing common standards is greatest. In sections on tagset guidelines and the Intermediate Tagset, this will be dealt with in some detail and in close relation to the standards for morphosyntactic categorisation in the lexicon.