@Aidan-Oxley When I want to know things like this I imagine the creators have documented the capacity of their tools in both the terms of their tool and the lexicon of other systems that perform similarly.
This isn't a new concept, but it's a very strange choice of word to use in a graphical environment for such a facility.
Mirroring is normally used as an alternative to flip, in any graphically oriented environment.
Referencing and Instancing are the common words for this kind of thing in coding.
If it works in ALL scenes, that the mirrored objects all pointing to the one object, then this is a shared reference to a common class or shared (single) instance of an object.
If only the source of the mirrored objects influences all other instances instantiated from the blueprint of the original (class),and are instances, not a strict reference (pointer) to a single instance.
This is a common choice available to anyone doing anything in programming and graphic design.
If you've seen symbols in Adobe Illustrator and Flash, or Smart Objects in Photoshop, each of them acts like a reference (all pointing to the same blueprint or class). In 3ds Max there are both types, instances and references, and the ability to determine the separation point between shared information and unique information. Which is VERY powerful for creativity.
In programming languages, Swift makes for a good example. There are two types of "mirroring". Value types are copies of the original, any changes to the copies has no impact on the original. Reference types share the same data between each instance of "reference" to the object. This is how mirroring should work. But who knows. I can't find anything about it in the documents.