: Along with the growth of Grid infrastructures, ubiquitous service provision and consumption has received wide attention in literature and practice. Although the number of available services rises rapidly, concepts and standards for an economical efficient service allocation remain in their infancy. Most proposed mechanisms lack of an interdisciplinary analysis that accounts for economical and technical requirements of the underlying trading objects. In this paper we reduce this gap by introducing concepts and prescriptive languages for describing IT services as trading objects. The contribution is a thorough and innovative classification of potential trading objects in Grid markets, an analysis of formal languages to describe these objects and an evaluation of potential market mechanisms for trading them.