So as I read it on page 291, all skills are modified by level regardless of proficiency. So a completely untrained lvl 20 pc with a 18 associated ability will still have a +18 modifier. A legendary indivishal will have a +23. That seems bizarre to me, even taking into account some actions can't be done untrained.
I find it bizarre that the explanation for Proficiencies is not located in the Skills chapter or before. It took me a while to find out what the dots on the character sheet mean.
