security support for testing distribution

I am trying to understand how the security support works for testing distribution. According to http://www.debian.org/security/faq.en.html#testing-security security support migrates from unstable to testing for any package. However, there is a separate testing security repository according

Re: security support for testing distribution

Does that mean that security updates go from unstable to testing security repository to testing distribution or am I misreading something here? No. If a (critical) vulnerability is discovered in some package which is already in testing or stable the security team patches it and uploads a fix