[jQuery] $.ajax success/error callback arguments, textStatus?

[henry]

reference: http://docs.jquery.com/Ajax/jQuery.ajax#options

What exactly is textStatus of the success and error callback argument?

Being a coldfuision user, I tried:
 <cfheader statuscode="403" statusText="testing123">

However, the textStatus is always the default value.

Any idea how to set textStatus on the server side? Thank you!