Kinda secret but not so secret that the symbols wouldnt be put all over the place like Freemasons do. Or stuff to flash in subliminal messages or something
Some examples of "others"
https://encrypted-tbn0.gstatic.com/i...jHHyZeU4cIxhAg
https://encrypted-tbn0.gstatic.com/i...tikiyaFl5m_-lQ
https://encrypted-tbn3.gstatic.com/i...F_7_oaOZaDIBZw
https://encrypted-tbn0.gstatic.com/i...jPHSnqQHkUD75A