guide lines Pubblico Deposited
Circular arcs, whose center is at the center dot, put onto a die blank to guide the workman (engraver, letterer, or apprentice) in entering letters, numerals, or stars. Normally they are polished off before the die is sent to press; occasional traces remained on some dies as late as the mid-1830s. They became obsolete with the introduction of complete hubs.
- Breen Encyclopedia