P2B1 means Person 2 Business. The 1 means this is the first term of its kind, and that there will be more
In summary form, P2B1 means “don’t track me off your site, and don’t let others track me on your site or anywhere else.”
Or, to sites that run advertising, it means this:
In machine-readable form, P2B1 is still in development. If you want to help with that, join IEEE Working Group P7012 – Standard for Machine Readable Personal Privacy Terms.