A presentation given to the UK 4D Special Interest Group in 2021 on the challenges present in Industry Data Models, using the Building Smart Industry Foundation Classes (IFCs). Despite diligent documentation and open publishing, the management of change in such domain models presents significant information management and software implementation (and maintenance) challenges. This presentation provides a visual illustration of the changes made over a 20year period to the IFCs. It also examines a publicly released dataset based on the IFCs, providing a visual overview of the entity types used. Additional comments are made on the challenges of using such models. Cytoscape files used for visualisations (including processed data from IFC analysis) and related images are provided.