Many reports, searches, etc. in VSys support the filter "Complex criteria". This filter is interesting and acts somewhat like an Intellilist. Unlike other filters, they also have the concept of an Action: this can be Add, Intersect or Remove.
In this example we're looking for people:
This wouldn't be possible without these complex criteria filters: normally a person must meet all of your criteria to be included. Here we're saying that they can either have matching hours or a photo (or both); you can only do that with complex filters. (The requirement that they do not speak Klingon or Dothraki could possibly be done by saying "None of" for those languages, but it's helpful as an example here.)
If we click on Edit for the first filter, we see:
It has an Action of Add, which means that people who meet these criteria will be included in the results. That means that someone must both have the skills and last volunteer hours in the right time range.
On the second, we see:
Its Action is also Add, but now things get interesting: where a normal filter would simply require that everyone have a photo, what this does is add the people who have a photo to the list of people VSys is already considering! This effectively tells VSys that a person qualifies if they're already in the prospect list based on previous filters they're good, but they're also good if they meet this filter even if they don't meet the previous ones!
The third is easy:
This - like normal filters - simply requires that everyone not be archived.
And the fourth removes people who meet its criteria rather than adding them (as in the first two) or simply requiring that everyone meet the criteria (the normal behavior):
Let's walk through this. What VSys will do is:
If we wanted to we could add another complex criteria at the end that added everyone from Albany, NY, regardless of whether or not they met any other criteria.
When you're using these complex criteria, you can see that order matters: if we did step four early, it wouldn't have the expected result.