Flat-Oval Tee
A round or flat-oval branch on the flat side of a flat-oval main: the main with its hole, and the branch cut to the main. A round or flat-oval branch set square onto the flat side of a flat-oval main: the main unrolled with its hole marked, and the branch with its foot cut to the main.
How the flat-oval tee is developed, with a worked example · Branches