Abstract : Compositional verification is a way to avoid state explosion for the enumerative verification of complex concurrent systems. Process algebras such as Lotos are suitable for compositional verification, because of their appropriate parallel composition operators and concurrency semantics. Extending prior work by Krimm and Mounier, this report presents the Svl language, which allows compositional verification of Lotos descriptions to be performed simply and efficiently. A compiler for Svl has been implemented using an original compiler-generation technique based on the Enhanced Lotos language. This compiler supports several formats and tools for handling Labeled Transition Systems. It is available as a component of the Cadp toolbox and has been applied on various case-studies profitably.