About 'cost' in repo conf?

[Sergio]

In the yum.conf manual is:
"cost:  relative  cost  of  accessing  this repository. Useful for weighing one repo's packages as greater/less than any other. defaults to 1000"

At first I thought I could use that to set a repo priority but it doesn't work (I set cost to both >1000 and <1000 and ran 'yum clean all' after any change to check). The latest version of a package is offered regardless of those settings.
So that 'cost' setting is only for packages of the same version in different repos?

I know there's a priority plugin for yum and I'll use it.

Best regards.