I want to have 2 separate web sites. One for computers and one for mobile devices. I have no idea what the code is for the browser to make that determination.

I read your problem alantran... But according to google latest update if you are creating mobile version of website with another domain it will cut your traffic surely.In Current market 60-70% mobile sites traffic share.So I advice to create a Resonsive Web Design of your website.That will increase your site trafffic surely.