What is the ACS protocol on Coinbase?

Could you elaborate on the ACS protocol utilized by Coinbase and its significance in the cryptocurrency ecosystem? As a practitioner in the field of cryptocurrency and finance, I'm curious to understand the functionality and potential impact of this protocol, particularly on the platform's overall operations. Does it enhance transaction security? Improve scalability? Or does it play a role in facilitating the integration of new digital assets? Your insights into the ACS protocol would be greatly appreciated.