In case you mutually refine several building blocks at once (as proposed in tip 5-25 (mutually refine)), you should explicitly document the origin (aka ancestor or root) of the refined building blocks.

It should be explicit for every element within a refined whitebox where it’s originating (that means, where it is refined from).

You find two examples below:

Document origin by naming convention

whitebox with two blackboxes refined to single whitebox

Document origin by graphical means

In the next diagram the origin of the refined building blocks is shown by a named rectangle around the refined blocks (for illustration purposes shown in pink color…)

refined building blocks