What application are you using to make the postprocessor? Is it Post Builder or Post Configurator?
You can use the Review Tool in either case to see the available mom variables and their values with each MOM event. Set Review Tool to On at the bottom of the Postprocess dialog when posting tool path.
If you are using a Full license of Post Configurator, you can see a similar, more detailed view using the Inspect Tool in the debugging options.