set yum priority on CentOS 5.5

I want to install yum-priorities plus-in so that the yum install or update priority is stable from official to third-party.

After executing the following command, we can see some .repo file locate on the folder "/etc/yum.repos.d/" like CentOS-Base.repo, and so on.
Next step,we will add priority=N (N=1-99 and priority order is from 1 to 99) on the content of these .repo files.

In some article,someone suggest the priority value is as follows rule.

• [base], [addons], [updates], [extras] … priority=1
• [CentOSplus],[contrib] … priority=2
• the third-party repository … priority=N （maybe set N>10）

So I follow this rule to set my CentOS priority value.

After done it, how to verify whether yum install or update follow priority rule?
You can first execute "yum check-update" command to realize whether "priorities" this word show the postfix of "loaded plugins". If you can see it, I think it will be good beginning.

Unfortunately,I cannot install or update PHP the special repository as webtatic then. How to force to install or update PHP by webtatic repository?
"We can temporarily disable ALL and enable webtatic repository by command."

So do that we did can successfully update PHP from 5.1 to 5.3.3 by yum.