On the Relationship between Use Case Maps and Message Sequence Charts F. Bordeleau 1 , D. Cameron 2 1. School of Computer Science, Carleton University, Ottawa, Canada emails: francis@scs.carleton.ca 2. Nortel Networks, Ottawa, Canada email: dcameron@nortelnetworks.com Abstract The time it takes to develop telecommunication standards must be reduced to allow companies to get features to the market faster. In order to achieve this objective, a process based on the combi- nation of a set of modeling techniques has been proposed by Nortel Networks in the context of the Wireless Intelligent Network (WIN) standard development. This process combines the use of standard notations like Message Sequence Charts (MSC), Specification and Description Lan- guage (SDL), Abstract Syntax Notation One (ASN.1), and Tree Tabular Combined Notation (TTCN). It also includes the use of Use Case Maps (UCM), a graphical high level scenario mod- eling technique, for stage one user requirements descriptions. UCM, which is not yet a standard, is going to be proposed as a candidate solution when ITU-T Study Group 10 meets later this year to consider Question 12/10 - URN: User Requirements Notation. In this paper, we introduce the UCM modeling technique, and discuss the relationship between UCM and MSC. Moreover, we define a transition that allows moving from UCM to MSC in a systematic and traceable manner. 1. Introduction Telecommunication standards are becoming more and more important as the pressure to deliver the unified network to every corner of the globe grows. Delays are being met with increasing impatience. We are involved in a line of research aimed at reducing the time it takes to develop telecom- munication standards and thus reduce the time it takes to get features to market. This research has been commissioned by Nortel Networks people participating in the development of the Wireless Intelligent Network (WIN) standard. The WIN standard writers are feeling the pressure of oper- ating companies who want product now to satisfy a growing demand from their customers for features. Our sponsors feel differing interpretations of text-based specifications is the principal reason behind the delays experienced in getting standards issued. Our sponsors and their colleagues have proposed two notations in an effort to mediate inter- pretations in the WIN standard forum [6]. They have proposed and introduced Use Case Maps (UCMs) [4] for stage one user requirements descriptions and Message Sequence Charts (MSCs) [7] for stage two roaming information scenario descriptions. While MSCs is a well known and widely used notation, the UCM notation is relatively new. It has been developed by Ray Buhr,