Good morning, There is a number of functions in the new l3sys package for testing the current engine, but I am still missing a public interface for testing the driver. The l3drivers package internally uses some mechanism to distinguish between pdfmode, dvips, dvipdfmx and xdvipdfmx. Will there be such a testing be included in the public interface of expl3 one day? Currently, I am still using a combination if the `ifpdf' package and the \*_if_engine* functions for the purpose of driver detection. Kind regards, Alexander