What happened if "Active" is unchecked in "Resource" definition screen?

I'd like to know what happened if "Active" is unchecked in "Resource" definition screen.

I'm expecting the result like followings:

   * The MH and Costs of Budget and Actual for past projects will remain intact.

   * The MH and Costs of Budget and Actual for past projects will be affected.

   * The resource cannot be assigned to future work.

      etc...

Could someone please teach me about the definition of "Active" checkbox in resource definition screen.

Sincerely yours,

Yusuke Tanaka