You may notice that was the whole of your initial post on this subject.

if you noticed Capitalised does NOT agree with your definition, thank you for admitting you were wrong about the USSR,
Okay, so you want to get into a pissing contest on whether it was capitalized or not?

Well, I think you should look at your initial post on the subject.

: a doctrine based on revolutionary Marxian socialism and Marxism-Leninism that was the official ideology of the U.S.S.R.
Yes, that is one definition of "Communism".

You might wonder why they included the phrase "official ideology".

No, you wouldn't wonder. You'd just parse for phrases.

So, if I said (as I did) that the USSR government claimed to be Communist, then that would make their "official ideology" Communism.

Not their "actual" ideology. Their "official" ideology.

Kind of like what our "official" reasons are for invading Iraq.