Component paths separated by a colon
A component in the component list of another object is always referenced by a colon (:). The local type name of the nested component precedes the colon. The name of the object that contains the component follows the colon. For example, the Line Item component of PO would have this name:
Line Item:PO
The Last Name component of Client, which is in turn a component of Account, would have this name:
Last Name:Client:Account