Stream Variables questions

Just an application that will “write down” the uptime for the streamer so when they are highlighting things all they do is type a description and the program handles the rest.

I’ve now noticed that even partnered streamers ‘updated_at’ field changes after going live. example…

stream created at: 9/17/2015 20:01:13
channel updated at: 9/17/2015 20:15:45

So what actually changes that field?