Most Speculative Mason’s have probably heard of Mason Marks.
These Marks were placed on stone work by stone masons so they would be paid for their work by the overseer of the project.
With Blue Lodge Freemason’s not being taught anything concerning Mason Marks within the lessons provided doesn’t mean that it isn’t an important part of the Speculative Ancient Craft.
I think one could say that we as Freemason’s apply the Mason’s Mark upon ourselves and our new Master Mason’s when we use the implements of the Craft properly in our daily walk on our paths of life.
Here is a very good YouTube video called, The Mason’s Mark Project.