The PortalSiteMapProvider class is the base provider used by the four default “CMS” SiteMapProviders:
GlobalNavSiteMapProvider
CombinedNavSiteMapProvider
CurrentNavSiteMapProvider
CurrentNavSiteMapProviderNoEncode
That is, all of these SiteMapProviders use the same base code to generate a data source, but their “output” differs slightly due to the different attributes that are applied.
Recently, we wanted to filter out the pages from showing up in our left-navigation. [...]