Pmstitch.xml files can be opened as master files by both the Atmos Mastering Suite and Atmos Production Suite.    Opening a pmstitch.xml in the Renderer allows you to playback and audition the stitch file before committing to performing the conversion in DACT.    It also allows you to audition the stitch file while the Renderer is slaving to incoming LTC and audition against video playback in your DAW.