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.
The principles of Freemasonry are used to assess the regularity and consistency of Masonic organizations like Lodges, Grand Lodges, and Grand Orient. These principles are considered fundamental and unchanging.