And just to be 100% clear, I have a bunch of systems — each of which has a PRO identifier — whose index is all in Bear, all thrown in there together. Each index entry is a note. There are many hundreds.
This is why Bear’s hierarchical tags, and the simplicity of the PRO.AC.ID notation, is nice. To find/show all BIGCO-DOF notes I can either filter by searching for BICGO-DOF., or just click the top-level tag in the sidebar.
(Also BIGCO-DOF is how I obfuscated this example, actually I use a letter and two numbers as outlined here. L43 in this case, which you may be able to figure out if you’re a spy. 
)