Section mode activates a section. Polygon mode inspects a polygon. Flatten, Flat Mesh, and Delete modes build export lists. Shift+click is a quick section select. Ctrl+Shift+click inspects a polygon.
Imported CSVs are only loaded into this browser session so you can review, edit, and export them again.
These polygons are at effectively the same click distance. Check one or more rows; Add Checked marks them in the current polygon mode.