Ubiquitous digial libraries are being developed with various web-based services. For the most part, these liraries support only searching, lending, and reservation services for users. However, the focus of a library's service should change from general content management to personalized service. For example, a library system should be able to predict what content a user is looking for, recommending it before the user begins his search. Such a libary system has to be aware of user's context, such as the user's id, access level, name, address, and interests. In this paper, we propose LIML(Library Interface Markup Language) to express user context awareness and provide personalized user interfaces in ubiquitous digital library environments. We show the validity of the proposed scheme with implementation results.