is http://www.cdtfa.ca.gov/industry/MPFAct.htm working?
Tax Guide for Marketplace Facilitator Act
http://www.cdtfa.ca.gov/industry/MPFAct.htm
A marketplace includes a physical or online place where marketplace sellers sell or offer for sale tangible merchandise for delivery in California. A marketplace facilitator is generally the operator of the marketplace.
Monitor availability and performance of your website, on-line shop or web application.