I want to write a code comment that means "every line in this file must be shorter than N". I wrote this:
No line in this file shall be longer than N
...then considered using "must", which is more commonly used:
No line in this file must be longer than N.
Intuitively, for some reason, I read the first as my intended meaning ("lines must be shorter than N"), but the second as "lines do not have to be longer than N), which is different.
I don't know of any rule that would give these two sentences different meanings, it is just how I intuitively parse it. I guess that I am wrong about at least one of them.
Do these two lines have the same meaning? Do they mean "every line must be shorter than N", or "lines can be shorter than N"?