I am creating pictures in TikZ.
Now, I have a certain C component, which consists of 4 nodes ( (a), (b), (c), (d) ).
I want to create 5 copies of this component, call them (A, B, C, D, E).
Then, I want to be able to draw lines between nodes of components. I.e.:
draw (A.a) (B.c); etc ...
My question: how do I create a "component" or a "grouping" in Tikz?