Re: Old-style backquotes in cc-vars.el

[Richard Stallman]

    I'm not sure whether the rules for nested backquotes are clearly laid
    out anywhere.

I think it follows logically from the syntax of one level of backquotes.
The inner backquote expands, producing a call to `cons' or `list'
which contants comma-expressions; then the outer backquote expands them.

I too found it hard to understand, and perhaps the code should be
rewritten to avoid nested backquotes, for simplicity.  But it is
valid.