The OMIS project aims at defining a standard interface between tools for parallel systems and monitoring systems. Monitors act as mediators between tools and the parallel program running on some target architecture. Their task is to observe and manipulate the program according to the tool's commands. A standardized interface will allow different research groups to develop tools which can be used concurrently with the same program. OCM, an OMIS compliant monitoring system, is the first realization of such an environment. It is designed for PVM programs running on workstation clusters. The paper will give an outline of the goals of this project and describe important details of the monitoring system's design.