It's not a secret. It's more like something painful that people don't want to talk about.

One thing that is interesting is that even among the government, people have different views

on Tiananmen. The last Premier, Wen Jiabao was the personal secretary to Zhao Ziyang, and he was highly sympathetic to the students. People within the government have different views about TAM, and so if you raise the issue then government officials are going to be arguing over that, and no one wants that.