After a brief reminder on general concepts used in data cataloguing activities, this chapter provides information concerning the architecture and design recommendations for the implementation of catalogue systems for the ENVRIplus community. The main objective of this catalogue is to offer a unified discovery service allowing cross-disciplinary search and access to data collections coming from Research Infrastructures (RIs). This catalogue focuses on metadata with a coarse level of granularity. It was decided to offer metadata representing different types of dataset series. Only metadata for so-called flagship products (as defined by each community) are covered by the scope of this catalogue. The data collections remain within each RI. For RIs, the aim is to improve the visibility of their results beyond their traditional user communities.