Legal Question in Appeals and Writs in California

Re: Argument

You can't, unless he is willing to tell you. You will find out when you receive his opening brief. You will then have 30 days in which to prepare your own brief, and should be able to get even more time if you need it. That should give you ample time in which to prepare.

You should get a lawyer to represent you if at all possible. Appeals are complex and are governed by very different rules from those which apply in the trial courts. I am a certified specialist in appellate practice (per the State Bar's board of legal specialization) and would be happy to discuss your case with you.