Hi Pierre, that was basically my question: Whether the server and the client belong into a single package definition with a modified build procedure and two outputs or whether server and client should be different package definitions because they are quite different but dependent. I would not want to make the server part the "out" output because the emacs part is what people are really interested in and the server is just a work around for the missing foreign function interface in older emacsĀ  versions and should be installed as a dependency of the emacs part. I need to figure out how to modify the build process accordingly but your reply answered my questions :) Thank you for your answer