The article discusses the role of linguistic annotation in corpus linguistics as opposed to annotation in natural language processing. In corpus linguistics, annotation is an integral part of the process of linguistic interpretation and description of the data. Tagging and parsing are discussed as the automatic counterparts of, respectively, the paradigmatic and the syntagmatic description of corpus data. The requirements for a corpus linguistic annotation system are considered. An account is given of the TOSCA analysis system as representative of such an annotation system. Performance results of the system are given, and an evaluation is made.