OPUS is a rechargeable, dual interface (contact/contactless) stored-value smart card using the Calypso Standard and is used by major public transit operators in Greater Montreal and Quebec City, Quebec, Canada. It complies with the ISO/IEC 14443 standard for smartcards, and can be read by smartphones with an NFC antenna. The name of the card in French, Carte OPUS, is a pun on the word in French for smart cards with embedded chips, carte à puce.