if (stepName != null) {
throw new XProcException(step.getNode(), "Step option can only be used when loading a p:library");
}
pipeline = innerRuntime.use(pipedoc);
} else if (XProcConstants.p_library.equals(piperoot.getNodeName())) {
XLibrary library = innerRuntime.useLibrary(piperoot);
if (stepName == null) {
pipeline = library.getFirstPipeline();
} else {
pipeline = library.getPipeline(stepName);
}