This Recommendation specifies service scenarios and high-level requirements for metaverse cross-platform interoperability. With the increasing number of metaverse platforms being developed, there is a need to create open and seamless interoperable environments between metaverse platforms that fosters innovation and collaboration. This Recommendation aims to identify the various intended service scenarios and high-level requirements of four types of metaverse cross-platform interoperability: avatar interoperability, asset interoperability, content interoperability, identity interoperability.