Masonic landmarks are a set of principles that many Freemasons claim to be ancient and unchangeable precepts of Masonry. Issues of the "regularity" of a Freemasonic Lodge, Grand Lodge or Grand Orient are judged in the context of the landmarks.
Masonic tenets serve as benchmarks for evaluating the structure and adherence to established practices within Masonic organizations such as Lodges, Grand Lodges, and Grand Orient.