Yes, you are right 
It is a Peg System since they are all pre-memorised concrete nouns which corresponds with the number digits.
And we use these pegs like a mental filing system that allows us to mentally file or attach the information for storage and retrieval.
I should have probably mention that, as a system it is known as the peg system.
I used the term “Method” as to how we apply the system by way of creating a Link between two items which I call “Pair Linking” Method if it’s just two items.
And of course what we mean by linking is the action we use involving the two or more items. For me, it becomes a Chain Link, if there are more than two items, it just makes more sense to me. That’s why I called it the Pair Linking as a Method.
Yes, that’s exactly what I mean by Pair Linking method.
If we then Link that final image to a Peg without placing it to a location, then we’d be using the Peg system.
With the linking method, we use it with;
Familiar (pegs) + Familiar (pegs) such as memorising number digits.
Familiar + Unfamiliar (not pre-memorised) attaching words/objects.
Unfamiliar + Unfamiliar, two items not pre-memorised linked by an action.
One of the examples for Familiar + Unfamiliar could be learning a foreign word where we attach an unknown word to a known word.
With the Link method, we can use pegs and apply an action involving the two, or more. We can use pre-memorised pegs, and or unfamiliar objects with other objects, which can then be either attached to a pre-memorised peg, or at a spot in your memory palace.
I mostly use the memory palace method, because even if I use the peg system, I still have to place the linked image onto a location.