The term 'legal tender substitute' refers to a type of currency known as scrip. Scrip is a form of currency that is issued by a company or organization and can be used to purchase goods and services from that same company or organization. It is not legal tender, meaning it cannot be used to pay taxes or debts, but it can be used to purchase goods and services from the issuer. Scrip is often used in situations where traditional currency is not available, such as in remote locations or during times of economic hardship.