Lets have the following AADL declarations.

A AADL model.aadl:

PACKAGE client_server_Pkg
PUBLIC
WITH AI;

SYSTEM client_server
END client_server;

SYSTEM IMPLEMENTATION client_server.others
PROPERTIES
AI::root_system => "SELECTED";
END client_server.others;

END client_server_Pkg;

A property set p1.aadl:

PROPERTY SET ai IS

Root_System : AADLSTRING
APPLIES TO (SYSTEM);
END ai;

A property set p2.aadl:

PROPERTY SET ai IS

Root_System : AADLSTRING
APPLIES TO (SYSTEM IMPLEMENTATION);
END ai;

Instantiating model.aadl+p1.aadl in Ocarina works.
Instantiating model.aadl+p2.aadl in Ocarina raises the error: " AI root_system cannot apply to client_server.others".