Re: understand Diff Formatting --cc flag?

Andy Zhang [off-list ref] writes:

quoted

Among 5 parents, perhaps parent#1 and parent#2 had the same contents,
and parent#4 and parent#5 had the same contents, different from what
parent#1 and parent#3 had.  You have 3 variants (parent#1's, #3's
and #4's; parent#2 has the same contents as #1, parent#5 has the
same contents as #4).

[Andy wrote:] as per your comments, The 3 variants are indeed into the
following 3 groups.
My question is: why can #1 appear inside multiple groups? A and B.
   <group-A> parent#1, #3, #4;
   <group-B> parent#2, #1;
   <group-C> parent#5, #4;

The three variants in my sample scenario were (A) used by #1, (B)
used by #3, and (C) used by #4.  #2 uses (A) and #5 uses (C).

The contents of #1 does appear twice, in #1 itself and also in #2.
That is what "#2 has the same contents as #1" means.

[Andy wrote:] can I explain  "--cc" flag as:
"--cc lists only either hunks which were modified from all parents, or
hunks which were modified from at least two parents and they had
different variants"

I do not have time to see if that matches the official explanation
found in "git diff --help", which I just re-read and I think it
gives the right definition.