\input zb-basic \input zb-ioport \iteman{io-port 01332631} \itemau{Etalle, Sandro; Gabbrielli, Maurizio} \itemti{On the correctness of the replacement operation for CLP modules.} \itemso{J. Funct. Log. Program. 1996, Article No.1 (1996).} \itemab Summary: In this paper we study the replacement transformation for Constraint Logic Programming modules. We define new applicability conditions that guarantee the correctness of the operation also wrt module's composition: under these conditions, the original and the transformed modules have the same observable properties also when they are composed with other modules. The applicability conditions are not bound to a specific notion of observable. Here we consider three distinct such notions. Two are operational and are based on the computed constraints; the third is the algebraic one based on the least model. We show that our transformation method can be applied in any of these distinct contexts, thus providing a parametric approach. \itemrv{~} \itemcc{} \itemut{constraint logic programming modules} \itemli{http://danae.uni-muenster.de/lehre/kuchen/JFLP/articles/1996/A96-01/A96-01.html} \end