I discovered the dependency directive some time ago, and filed a doc bug.
It appears to be only for Android, ARM and iOS platforms only.
Here's a usage of it in the Delphi RTL:
function DBXLoader_GetDriver(Count: Longint; Names: TWideStringArray; Values: TWideStringArray; ErrorMessage: TDBXWideStringBuilder; out pDriver: TDBXDriverHandle): TDBXErrorCode; cdecl; external LibName name 'DBXLoader_GetDriver' dependency VendorLib, LibCPP, VendorLibDep;
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes