This filter allows you to find similar frame geometries based on Stack and Reach. You put in the stack and reach of some bike, and a tolerance such as plus or minus 20mm, and then you see the frames that fall within that range. The expression is just three numbers separated by commas. Eg: Stack,Reach,Tolerance. For example, to find all the frames similar to the Brodie Romulus size 60, you would put in: 626,410,20

From the document: Bike Geometry Lister