Data files (205) are categorised in order to facilitate the searching for information. The analysis is performed in order to identify items which may be considered as having high value without actually being directly specified. Occurrences of unspecified candidate items are identified (207) in contexts for a preferred specified category. Occurrences of unspecified candidate items are identified (209) in non-preferred contexts. The preferred occurrences are processed (211) with the non-preferred occurrences for each candidate item in order to select candidate items as being high value items. In the preferred embodiment, data relating to companies is identified without specific company names being defined.