1. A machine-implemented method for identifying patterns in text using structures defining types of patterns which are to be identified, wherein a structure comprises one or more definition items, the method comprising: assigning a weighting to each structure and each definition item; searching the computer text for a pattern to be identified on the basis of a particular structure, a pattern being provisionally identified if it matches the definition given by said particular structure; in a provisionally identified pattern, determining those of the definition items making up said particular structure that have been identified in the provisionally identified pattern; combining the weightings of the determined definition items and optionally, the weighting of the particular structure, to a single quantity; assessing whether the single quantity fulfils a given condition; depending on the result of said assessment, rejecting or confirming the provisionally identified pattern.