Welcome to RenderPass Manager
RPManager is an extension of 3dsmax, intended to make the task of managing multiple render 'passes' from a single scene file easy and User Error free.
What is a 'Pass' and why would you want to render you scene out to multiple passes? Look here for a description.
Some of the problems RPManager was designed to over come are obvious, some not so obvious: The 3dsmax render dialog only has two slots - production and draft (and only one in 3dsmax6 and later) - which is simply not enough for the most basic of serious production work. More importantly, these two slots only store a certain amount of information - output path, render resolution - and not the amount of data that is needed for a complete pass - camera settings, object properties, object visibility, background setup, etc. The built in batch render tool is clumsy to use and limited in functionality.
Traditionally the user will either use a single file and manually edit parameters/scene setup to output the desired passes, or break the scene out to multiple files - which makes editing a chore and prone to error as the files need to be synchronised, usually manually. Both these methods allow too much chance for User Error and take up large amounts of time, especially at the end of a job where many small tweaks are often required.
RPManager overcomes many of these problems in two ways: firstly it allows unlimited render passes, and secondly it brings almost all render parameters into the one interface. The few less used in (a per pass sense) render parameters not included in the interface can be controlled through the BeforePass and AfterPass scripts - if you need something done per pass and it is not in the interface and it is scriptable, then RPM can still control this on a per-pass basis.
RPManager is a complex interface, there are over 30 rollouts and dialogs, and hundreds of individual controls. As such it can be a daunting tool to use at the start - but you will find that you quickly become accustomed to it once you are over the initial hurdle of getting used to the workflow. Enough control to really do what you want with render passes does mean a certain level of complexity is essential.
Use the list on the left to find out about how RPManager works.