How should a performance interface be developed to meet the goals for OpenMP? Although different interfaces are possible (see [5,10]), the basic idea behind our proposal is to define an API to a standardized performance monitoring library that can be used to instrument the user's application program. This instrumentation could be done by a source-to-source translation tool prior to the actual compilation or within an OpenMP compilation system. Performance tool developers then only need to implement the functions of this interface to enable their tool to measure and analyze OpenMP programs. Different measurement modes (e.g., profiling  and tracing [5,7,10]) can easily be accommodated in this way. In the following, we present various aspects of our proposal for a standardized performance tool interface using directive rewriting for its implementation. Fortran90 OpenMP 2.0 syntax is used in examples and tables. Of course, the transformations equally apply to C/C++.