Abstract. This paper reports on efforts to define a performance monitoring interface for OpenMP that merges the OMPI and POMP prototype interfaces developed in the past year. The primary goal is to define a clear and portable API for OpenMP that makes execution events visible to runtime monitoring tools, primarily tools for performance measurement. The proposed specification is presented, covering many relevant design issues and the result of discussions among the involved groups. Both successful convergence of ideas, leading to agreement on proposed specifications, as well as differences in opinion and remaining open issues are documented from our many discussions. The paper is intended to serve as a preliminary proposal for consideration by the OpenMP Architecture Review Board and recently formed Tools sub-committee.