If it's not in the BK estate, you don't need to exempt it. But if you insist on attaching an exemption to it, use 703.140(b)(10)(E) and check "unknown"
Of course there is a known value for your interest in CALPers, it is just that you have made no effort to find the value. I would suggest that you either contact the system administrator for valuation help or learn to estimate pension values before putting down a value. If you are having trouble with your exemptions, you probably ought to have legal representation, because it will be the issue you don't see to worry about that will kick you in the behind. Hope this perspective helps!
All debts and assets must be disclosed, including your interest in retirement/pension/profit sharing accounts. Generally, the amount is fully exemptable. You need to consult with a BK attorney in order to properly select your exemption schedule. You must use the same schedule for the entire case and are not allowed to mix your exemption schedules. In my 37 years of practice, I cannot recall omitting any retirement account from the personal property asset Schedules.