Omnibus, internal transactions without gas fee, when?

The documentation, Create Direct Custody Wallets, says that with an omnibus wallet structure there is no gas fee for internal transactions.
What counts as internal transactions in this regard?

Hi @fredrikl–when the article mentions no fees for settling transfers within an omnibus wallet structure, it refers to settling operations on an internal and off-chain ledger to track customer funds.

When an omnibus wallet structure is used, any funds kept on the platform are generally swept into a single vault. In this architecture, customer funds are stored in a single vault, and any movements of funds between customers can happen in a ledger system maintained by you. This ledger can reflect transfers, sales, or purchases as needed, and you can credit/debit customers on this ledger despite no operations taking place on-chain. This means no on-chain fees are charged given operations are settled on your internal ledger.