Converting "NA" and "N/A" field values to nulls
Generated test data for an association rules model
Testing different forms of the OutputField element

PMML schema versions 4.0 and 4.1 use a combination of "feature" and
"ruleFeature" attributes to select a rule value from an association
rules model. Starting from PMML schema version 4.2, the list of feature
identifiers includes all rule feature identifiers, and the use of the
standalone "ruleFeature" attribute has been deprecated.