Play call pictures

[NJPHINFAN79]

Mods feel free to move this just looking for a quick explanation.

watching some of the Clemson game because dalton is embarrassing to watch and they have, similar to Oregon the poster boards w four pics as their play calling signals... How does this work? I read a quick explanation from 2010 from Oregon but it was pretty vague.

Its gotta help with tempo, but is it easily decoded? How come we don't see it In the nfl...

Is it just really for basic/limited number of options?

 

[Third Eye]

Um we don't see it in the NFL because the NFL has a radio in the QB's helmet where he can hear the play call said to him from a coach. The NFL does not typically use signals from coaches for play calls.