Which tables are "the network database tables" I " will need to empty or remove"

I have numerous times followed the codex instructions on Creating a MultiSite network. I have done this successfully on other installations. However, on this one, each time, there comes an instruction for which I cannot find any guidance whatsoever:

“Warning: An existing WordPress network was detected.

Please complete the configuration steps. To create a new network, you will need to empty or remove the network database tables.”

I make the precise additions to wp-config.php and .htaccess. Fine.

But no where do I find documentation on which tables these are. I am sort of dumbfounded by the number of users REPORTING this instruction in a lot of closed threads with no answers.

So I know I’m not alone. But is someone trying to keep a secret about which tables these are?

I’m not even sure I have them; but I keep starting this Groundhog Day over, and nothing gets better. So I thought I’d ask.