What exactly does 'anti theft mean on my volvo car radio/cd player?

I took it out of my car before I scrapped it and now I want to sell it. If I sell it will it play in somebody Else's Volvo (Volvo car stereos only play in Volvos). I don't want to sell it and It then won't play!|||Eather it wont play in another volvo. Or sometimes you need to take it to the delership because the require a code and they charge for that. I know. It sucks