The optional MiningBuildTask element in PMML, which allows free-form content, seems like a great idea to me.  I often want to record information for future reference about the parameter settings used in training and potentially statistics about the training process.  I have my own thoughts about what to include in this element, but would be interested in pointers to best practices, or good concrete examples, of using this element.  Surprisingly, this element is not even discussed in the Guazzeli, Lin, Jena book.