Username in the the identity document

Hello, I don't know If in your country exists the identity document also called identity card. I'm from Spain and I've it. In our times, the username is so important for the administration and the organizacion as a second name on the Internet. I think that the governments have to create an unique username for us in the Identity document, and then we'll be able for administrate better our dates on the Internet. Also we could recognize better in our relationships. In this century, the identity document have to be allied with the new technologies. I don't know what's your opinion but I'd to know. Thank you

Does that mean no matter what site you register to you can only sign up using that one username shown on your identity document?

I see this person is now a guest so no need to reply to this topic.

would that be safe if you only have one username in all your account?