A software component that detects entities or units of information in a text document, such as product numbers, based on regular expressions that describe the exact patterns that are searched in the document text. If one of the regular expressions matches parts of the document text, the regular expression annotator creates the corresponding annotations that cover the match or part of it. These annotated expressions are then stored, either in the enterprise search index using an index mapping file, or a JDBC-capable database using a database mapping file.