Today I received the same answer with the, A GTS Email Printout is ideal, in it.
I too had no idea what it meant and even after reading this, I still had no idea so I asked Gigabyte what it is.
I got a reply but it was not a straight forward answer but after a bit of thought I have concluded that the GTS stands for Gigabyte Technical Support. (D'oh)
So they are asking for a printout of the Gigabyte Technical Support email. However, the email I got just told me that they had answered my question and that I should click on the link to see the answer.
As the answer has the product number at the bottom of it. It should have said, a printout of this answer would be ideal.
Robert