You can use org// to identify an enterprise root. In essence, org// is an alias or functional equivalent for .../domainname/. When using org//, the double slashes identifies the root enterprise context and namespaces associated with it.
For example, org//site/alameda names the Alameda site associated with the enterprise root.
In contrast, org/ or orgunit/ (with a single slash) points to an organizational context which is not necessarily named relative to the enterprise root. For example, org/sales/site/alameda.