External module in the NCBI Book DTD (and NCBI Collection DTD) that declares Parameter Entities of element class definitions to over-ride element classes in the base DTD Suite
<!ENTITY % bookcustom-classes.ent PUBLIC "-//NLM//DTD NCBI Book DTD Over-ride Classes Module v2.2 20061013//EN" "bookcustom-classes.ent" >
bookcustom-modules.ent