| To be concrete, I propose this:
Not concrete enough. I don't understand
| prefix with a ( before the .: field selector
| otherwise: field access
What does (f a .b c .d e) mean?
According to my table, we have two prefix `.`s. These are field accesses. Just like the tight infix positioning of `.`. So, (f a .b c .d e) means the exact same thing as (f a.b c.d e), which is, presumably (f (a.b) (c.d) e).
Perhaps that's not what we like. But it is simple and comes straight from my table. And it is not too bad for programmers: prefix `.` is *just like* tight infix `.`. The only exception is at the beginning of a section, where tight-infix does not make sense.