X9.138-2020 defines terminology for blockchain, digital currency, and distributed ledger technologies (DLT) for use in the financial services industry. These defined terms are intended to assist regulators, inform future legislation, and provide consistency in the development of future X9 financial services standards. A standardized vocabulary will help remove barriers to the adoption of new technologies that can improve operating efficiency in financial services, reduce cost for banks and their customers, and lead to greater understanding in our legal and regulatory community. The scope of this standard includes terms used to describe blockchain, digital currency, and DLT. These include terms related to business, legal, legislation, and technology.