In this paper, the characteristics and the efficiency of several existing open format specifications for PPP/PPP-RTK services are analyzed, and a general message format for satellite-based open PPP/PPP-RTK services to maximize their interoperability is proposed. The interoperable format is defined as an extension of Compact SSR, a highly efficient RTCM-compatible open format applied for QZS CLAS. The format needs to support the global-scale PPP service as well as nation-wide PPP-RTK service using the constellation of MEO/IGSO/GEO satellites. To support global PPP using a multiple satellite data link and multiple generations of GNSS constellations efficiently, the satellite grouping using multiple satellite masks is introduced. The consistency and the resilience of the SSR correction messages under the condition of partial loss of messages are discussed. For the case study, the format is applied to a global PPP service using MEO constellation and a nation-wide PPP-RTK service using IGSO/GEO and analyzed.