The document discusses challenges in converting R models to PMML format and solutions using the r2pmml package. Specifically, it addresses issues like tightly coupled R scripts and model objects, lack of standardization, and inability to deploy models outside of R. The r2pmml package allows decorating model objects with supporting information and converting them to PMML, addressing these issues. This standardized format represents the R workflow and data using PMML structures, enabling "train once, deploy anywhere". The document provides examples of converting various R models like GLM and transforming features to PMML.