Supplying a default initial STATE to parse-partial-sexp. What about elt. 9?

[Alan Mackenzie]

Hi, Emacs!

In a function, I want to parse-partial-sexp through a buffer,
successively feeding its result back as the STATE parameter of the next
call.

To avoid an irritating special case, I'd like to initialize the state to
a default value, rather than passing in nil.  Something like:

(let ((pps-state '(0 nil 0  nil nil nil 0 nil nil nil)))
              ;;   0   1 2    3   4   5 6   7   8   9
  ....)

However, this leaves me a bit uneasy about the 9th element, which is
documented as "Intermediate data for continuation of parsing (subject to
change)".  Is it valid to set elt 9 as nil, or will this cause some sort
of malfunction or signal in parse-partial-sexp?

Thanks in advance!

-- 
Alan Mackenzie (Nuremberg, Germany).