A blaze is a mark made on a living tree by removing a section of bark from the tree to expose the light colored heartwood. Blazes left scars that could be discerned long after the bark healed over the wound.
In the PLSS, section numbers and other identifying information were inscribed on the heartwood. If necessary, a professional land surveyor may remove the grown-over bark to confirm the inscription. Amateurs should not disturb blazed trees.