On 4/19/20 2:01 PM, Drew Adams wrote:

> 'foo returns the symbol foo.  Depending on the
> context, you can certainly modify the properties of
> that symbol - its `symbol-value', `symbol-function',
> and `symbol-plist'.

Thanks for catching that. I installed the attached further patch to fix that.

> The message should be about not _depending_ on a
> quoted value returning a new object (e.g. new list
> structure).  The message should not be that `quote'
> never returns a new object.

The message is already in the new "Constants and Mutability" section in the 
emacs-27 branch. No doubt the wording could be improved....

> A constant is not something that _should not_ be
> modified.  It's something that _cannot_ be modified.

This is merely a terminology issue; feel free to come up with better terminology.