Configuration : External Identity Mapping

Hi All,

I am new to cognos admin, I am trying to enable SSO b/w cognos and websphere portal. I am able to see the cognos report in portlet if I allow anonymous login as true, but for SSO configuration I set to false, and have done the required things like creating authentication namespace etc. infocenter says that we need to set “Use External Mapping” to true and set “External Identity Mapping”. But I don’t understand what are these two parameters and what values to set for these - “Use External Mapping”, “External Identity Mapping” Please suggest what is significance and values that are to be set