The invisible code of language, which we can speak and use. Right and wrong. Let's take a one-minute story, and try to describe what it is made up of. Then let's write our comments down, and look at the page again. This is the core of something which we can call Structure or Grammar.
Words functioning in sequences, how they work, what ideas they carry.
I feel OK Je m'appelle. . . Analysis of a page of writing in terms of this framework, optionally using a color stripe for each function. A shorthand system of notation for correcting errors in written English, used as a convenience rather than a rule.