Call-by-reference semantics for RPC
The idea is to be able to modify the argument. FORTRAN used call-by-reference always, Algol-60 used the (mathematically clean, but hard to implement and with surprising corner cases) call-by-name; Pascal distinguishes between call-by-value and call-by-reference ("gets the variable"). But call-by-reference has its surprises, introducing aliasing between variables. Thus Ada offers call-by-value-return too.

If caller and callee reside on different machines, the performance gain of not copying arguments in and out, just using a pointer, is lost. Even worse, doing call-by-reference is quite inefficient (need to copy back and forth each time something changes). If you are defining what to do, I'd just ditch call-by-reference, and fight users tooth and nail to keep it out.