IN KLAUS POHL, PATRICK HEYMANS, KYO-CHUL KANG, AND ANDREAS METZGER, EDITORS, FIRST INTERNATIONAL WORKSHOP ON VARIABILITY MODELLING OF SOFTWARE-INTENSIVE SYSTEMS (VAMOS), NUMBER 2007-01 IN LERO TECHNICAL REPORT, PAGES 171-176, LIMERICK, IRELAND, LERO - THE IRISH SOFTWARE ENGINEERING RESEARCH CENTRE, JANUARY 2007