A number of theoretical studies have been devoted to the notion of sublanguage, which mainly concerns linguistic phenomena restricted by the domain or context. Furthermore, there are some successful NLP systems which have explicitly or implicitly addressed the sublanguage restrictions (e.g. TAUM-METEO, ATR). This suggests the following two objectives for future NLP research: 1) automatic linguistic knowledge acquisition for sublanguage, and 2) automatic definition of sublanguage and identification of it for a new text. The two issues become realistic owing to the appearance of large corpora. Despite of the recent bloom of the research on the first objective, there are few on the second objective. If this objective is achieved, NLP systems will be able to optimize to the sublanguage before processing the text, and this will be a significant help in automatic processing. A preliminary experiment aiming at the second objective is addressed in this paper. It is conducted on about 3 MB of W...