Remember how you started out with a couple of slide collections with just a few slides in each?
Your content has gradually grown, and you now have content that more represents the real world: multiple slides and stains are grouped by patient and represent real-world cases.
Showing all of your slides as a single list becomes messy, and so you'd rather see the slides grouped properly.
You can do this by creating a new level of hierarchy in your folder structure. For any case that goes under bladder, you create a new folder, and move the corresponding slides over to their new location.
You can prepare the data in PMA.start, or in PMA.core alike.
The result is instantly visible in the PMA.slidebox front-end interface.