| ## 6 Structuring Specifications Michel Bidoit1 and Peter D. Mosses2 1 Laboratoire Spécification et Vérification, CNRS UMR 8643 École Normale Supérieure de Cachan 61, Avenue du Président Wilson, 94235 Cachan Cedex, France `bidoit@lsv.ens-cachan.fr` 2 University of Aarhus, BRICS and Department of Computer Science Aabogade 34, 8200 Aarhus N, Denmark `pdmosses@brics.dk` Abstract. Large and complex specifications are easily built out of simpler ones by means of (a small number of) specification-building operations. In the previous chapters, we have focused attention on basic specifications and detailed how to use the various constructs of CASL to write meaningful, but relatively simple, specifications. The aim of this chapter is to discuss and illustrate how to assemble simple pieces of specifications into more complex, structured ones. In particular we explain how to extend specifications, make the union of several specifications, as well as how to rename or hide symbols when assembling specifications. Parametrization and instantiation of generic specifications are explained in the next chapter. LNCS 2900, pp. 67 - 75 Full article in PDF lncs@springer.de © Springer-Verlag Berlin Heidelberg 2004