ORAC-DR searches in two locations for the recipe files. First, the directory specified by the ORAC_RECIPE_DIR environment variable, if defined, is searched. This allows users of the pipeline to modify a standard recipe without editing the original. If the variable is not set or the recipe can not be found, the default location of $ORAC_DIR/recipes/$ORAC_INSTRUMENT is searched (although oracdr can sometimes be used to modify the value of ORAC_INSTRUMENT during initialization). The pipeline aborts if the recipe cannot be located.
ORAC-DR -- Programmer's Guide