A single, but different numbered point, enters a group for one second.

I want to create one particle every time a point enters this group.

~Shawn

the grouping is done by the box in this case but you can easily use any points and any method of grouping you want.

ask if you have any questions

Ahhhh, thank you!
I needed the delete sop.

I modified your file since none of the nodes where connected (is that so I have to connect them and learn?). And I couldn't get the Solver SOP to work or find any help on it. Isn't it used for DOPs?

I ended up using a group sop. There is a switch that shows how I animated the second box to select one point on one frame. I'm sure there is a better way to make my group smarter:

If the group looked at itself every frame and input “numberOfPoints” into an attribute, then at the next frame it could see if this value changed. If no, delete all points in group, if yes then keep point. Still, I'm finding this tough to do. Really wanted to have a bounding box select a large group of points but only emit one particle per new point in selection. Think of a paint brush adding paint. The brush head might be large or small but only add paint to points once as it moves along a surface. The group from the brush would birth a particle and I could use color/alpha to make paint dry.

i opened the file again, and everything is indeed wired and doing what you asked. its working for me in 12.1.49 what build are you running? maybe try re downloading it?