Question

a point is represented by a single dot and a lower case letter right?

Answer 1

A point is often represented as an upper case letter.
Sometimes with a letter and an index number, actually there is a fair few notations that I have seen.

Answer 2

It can be represented by a dot, however it has to be capital, and if you see a lowercase italics letter on your graph like: \[n\] then that means that the name of that plane is called "n"