Location-based services (l-services for short) compose an emerging application involving spatiotemporal databases. In this paper, we discuss this type of application, in terms of database requirements, and provide a set of ten benchmark database queries (plus two operations for loading and updating data). The list includes selection queries on stationary and moving reference objects, join queries and unary operations on trajectories of moving objects. We also survey recent work in query

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... ng for those query types, with emphasis on indexing of moving objects, and suggest candidates for efficiently supporting databases for l-services. (*) Also with the Data and Knowledge Engineering Group, Computer Technology Institute [http://dke.cti.gr]. 2001). To our opinion, it is partially both; moreover, it is due to the lack of a clear understanding of what kind of management should a MOD offer, what is the expected functionality, in terms of user interfaces, the SQL or SQL-like query language provided, query processing and optimization issues. Recent basic research (in particular, in the European 'Chorochronos' research network (Sellis et al., 2002) ) covered a wide spectrum of applications involving space and time, from continuously to discretely (i.e., elevation) moving objects or regions, to stationary objects changing other (non-spatial) information over time. In a previous paper (Theodoridis et al., 1998) , we classified spatiotemporal applications as follows: o With respect to the dataset mobility: growing, evolving or fully-dynamic; for those involving stationary objects of varying cardinality, moving objects of fixed cardinality, or moving objects of varying cardinality, respectively.