2.2.49.7.2 Method Equivalence
Any AIDL method that does not have any parameters with the lcid or retval attributes MUST map to an ODL method with the same argument types, and a void return type.
An AIDL method with a parameter with the lcid attribute MUST map to an ODL method that is equivalent to the AIDL method with the lcid parameter removed.
An AIDL method that has a parameter with the retval attribute MUST map to an ODL method whose return type is the type of the retval parameter, with one level of indirection removed. The argument types of the ODL method MUST correspond to the arguments in the AIDL method, with the retval parameter and any lcid parameter removed.
For an example illustrating this, see section 4.2.