They ask you to sign those, but the state doesn't permit them to claim inventions done on your time on your equipment. Don't be fooled.

What exactly constitutes "your time"? Is there a legal definition for this that appeared recently?

I had a long-drawn out conversation with Chris DiBona about this very question, and the answer is that it's very very murky, and most of the time -- even in California -- the corps can win.

You will still want to work with the company so there is proof that you both agree you are exempt.

You can't sign your rights away. The company document is void.

I'm not arguing that. Completely disregarding the void document, you will still want to document _and notify_ the company that your IP is in the exempt category.

I'm assuming the law is similar to Kansas Statute 44-130[0]

(d) Even though the employee meets the burden of proving the conditions specified in this section, the employee shall disclose, at the time of employment or thereafter, all inventions being developed by the employee, for the purpose of determining employer and employee rights in an invention.

[0]: http://www.kslegislature.org/li_2014/b2013_14/statute/044_00...

Ah! I'm following now. I'm not sure about CA disclosures. I know the Delaware company I'm at now, asked for one.