This paper discusses issues that arose in an effort to transpose the semantic and methodological value of HRT-HOOD into a carefully-crafted selection of the UML meta-model. The main goal of the project was to prevent the massive advent of theUMLfrom obliterating the unique strengths of theHRTspecialisation of HOOD for the support of real-time design. Avoidance of closed conservatism also afforded the project the opportunity to reflect on aspects of object-oriented design that may arguably benefit the resulting HRT-UML method.