I remember watching a documentary about the Ordnance Survey department and it mentioned that the artists would hid their name in things like rivers because they

I remember watching a documentary about the Ordnance Survey department and it mentioned that the artists would hid their name in things like rivers because they did not get official credit. I think it is somewhere in https://www.youtube.com/watch?v=w5_kWzUahQU https://www.youtube.com/watch?v=w5_kWzUahQU