Abstract : A high-resolution process timing facility, called HRTIME, has been implemented for the Cedar system. HRTIME is an extension of the Concentrix USER and SYSTEM process states with 10 usec accuracy. In addition, HRTIME provides individual processor timing measurements to give a detailed account of the time spent in various states of sequential and concurrent execution. The main purpose of this manual is to explain how to use the HRTIME facility. In particular, the manual discusses how to access the timing data, to correctly time a program section, and to interpret the resulting time measurements. Although a brief overview is given describing what the time measurements are and how they are produced, the user should refer to BELM87 for a complete discussion of the HRTIME design and implementation. Keywords: Multiprocessors, Fortran, Program compilation.