Search engines are now tools of every day life, Google being the most famous example. While they allow to access easily Internet documents, they are more and more used, under the denomination of "enterprise search engines", to manage the considerable amount of documents that constitute the memory of entreprises. We present the ground of a search engine that aims to propose a unified vision of the different documents formats (HTML, XML, Word, Mail, etc. but also data from databases) and to make search into these documents transparent to the user.