Pass – is the foundation of the LPM structure.
Pass name should be understandable and meaningful to someone who works with file for the first time, to understand what is happening in each pass.
The names of the passes may be the same, but in order to avoid overwriting the final result on rendering, it is recommended to give a unique name to each Pass.
The passes can be stored in the root of the LPM tree structure, and in groups that are useful when a large number of passes.
Clicking on the pass icon, you can make it active or turn it off. Inactive passes are not considered in the final render. Depending on the configuration of pass, it can:
– does not affect the visibility of objects and lights
– hide all objects and turn all lights off
– make all objects visible and turn all lights on
It is recommended to use the second option, for each new pass to be like empty sheet, which is filled as you add objectsets and lightsets.
There is another type of pass – Adjustment pass. It’s a special kind of pass, which must have the parent pass. This means that at first all settings of the parent pass apply, and then adjustment pass settings apply.
The pass provided the opportunity to override root folder, and name template.
You can save the final result in *.vrimg format  and automaticly convert it in *.exr using, Vray tools.