Problem frames are a sound and convenient approach to requirements modeling. Nevertheless, they are far less popular than other less rigorous approaches. One reason is that they employ a notation that is neither very appealing nor easy to use. The problem frames notation is sufficiently different from other development languages –especially UML– to create an “impedance mismatch”: using problem frames to describe requirements does not help the transition to the design phase, makes it difficult for programmers to fully comprehend requirements, and does not favor traceability. As a consequence, problem frames are rarely adopted in software development processes employing UML as a design language. UML itself provides a linguistic support for re...