This document discusses adding a MASSBAL sub-flowsheet in HYSYS. It describes entering material streams and unit operations from a MASSBAL case file into HYSYS to generate simulation results. The MASSBAL file uses a graphical interface to define streams, units, and case specifications in a text file that HYSYS then translates and simulates. Key differences between HYSYS and MASSBAL stream definitions and naming conventions are also outlined. The document concludes by noting configuration options available on the Parameters tab for the MASSBAL solving process.