I am using more and more commands from the cli wallet and am curious about the following when restoring a wallet:
./monero-wallet-cli --generate-new-wallet mytestwallet --password="blahblah" --restore-deterministic-wallet --electrum-seed="$(< mnemonic.txt)"
monero-wallet-cli will then prompt:
Enter seed encryption passphrase, empty if none:
1) If I leave it empty, the wallet is generated properly from the specified mnemonic seed.
2) If I enter something a wallet is generated with a different mnemonic seed.
Where in the creation process can I even enter a mnemonic seed password?
Is this legacy for old wallets with 12 word mnemonic + passwords?