This post is more informational than needing help with a problem:
I have found what I think is a bug with the current version (2.2.21)
On the Columns and values page of the Wiki HERE [PortalSettings.PortalAlias,System] does not return a value. I did find, that by reviewing the old ListX docs and looking at some of my own old code that [PORTALPATH,system] does return a value, but it is not in the documentation on the web site. [alias,system] does return a value.