yum-daily.yum - FC4

[linux]

Does anyone know what the yum-daily.yum file does? It's in the /etc/yum
directory, and is called by"yum-daily.yum" the daily yum cron job
in /etc/cron.daily/yum.

I can't find a man page or a faq or a howto anywhere which explains this
file. It's new for FC4

It has three lines:

update
ts run
exit

I can see update prompting a "yum update"
but I can't figure out "ts run" - is it a test run?

I assume "exit" gets out of the yum process.