My mistake. I wanted to write addresses. Thanks for pointing this out, I edited my original post.
To reformulate my question: when I send out to other addresses what method is used by bitcoin-cli to decide which addresses are debited (to use a more banking word)? Because, at the end I will have a deducted balance on one or more of the above 10 addresses, as I "spend" some of my bitcoins, right?
There are no addresses in transactions or in the blockchain.
Addresses are used in the human interface of wallets.
The wallets use those addresses to build transactions.
What is actually stored are transactions (and transaction outputs). NOT balances.
To show you a wallet "balance" the wallet adds up all the outputs that it has control over and displays that sum to you as a "balance", but the outputs aren't literally combined.
To show you an "address balance" on a block explorer website, the block explorer adds up all the outputs that were built from the same address information and displays that sum to you as a "balance", but the outputs aren't literally combined.
I suspect that what you want to know is:
"When choosing from the unspent outputs that the wallet has control over, what criteria does the wallet use to choose which outputs to spend?"
If you want to know about "accounts", that's a different subsystem in Bitcoin Core that is completely under the control of the user and has nothing to do with the actual transactions created.
As for the answer to the unspent outputs question... I unfortunately don't recall the specifics of that. With a bit of research I could get you the answer, but don't have time for that at the moment. If you don't have an answer from someone else by the end of today, I'll take a look at the code and see what I can figure out for you.
