The CEN 13149 series of products concerns on-board data communication systems on public transport vehicles. This series provides for data services that enable open and managed sharing of relevant information. This document, being Part 9 of the series, specifies a time publication, enabling all on-vehicle services to share a common understanding of current time, based on a suitable agreed master network clock. It covers: the functional scope, i.e. which data the service provides, why, when and how often. the transport protocol, i.e. how the data are transmitted. the service publication, i.e. how the service can be found by other modules or applications the structure of the data, i.e. how the data are structured and how the data elements are named. This document implements the service framework described in FprCEN/TS 13149-7.