When a new requirement is developed in the XSLT stylesheets, special test XML sources are created. Normally, the source folder in the file system contains all source XML files, which the new test XML sources are added to. Processing the whole source folder is necessary to avoid regressions. But this takes a couple of hours and, during stylesheet development, only the new test XML sources are relevant. So that the source folder does not have to be changed manually, an easy way to use another source folder and/or a specific file filter is needed. The XProc 3.0 pipeline should be able to use a custom source folder and/or a specific file filter as invocation parameters.