SDM employs a set of basic protocols that underly the usages described
in Section 3. SDM delegation protocols specify what information gets
exchanged when an object A invokes a method on object
B. The underlying layer must determine the delegation mode
to be enabled from the context and security requirements attached to
the target (remote reference B). Thus, the security policy
for an intermediate object governs which privileges and delegation
mode to apply at any given context. (See Figure
.)
Different rules apply for each of the combinations of required and
specified modes that can occur in a sequence of invocations from
object A to object B to C. (i.e
A 
B C):