This document provides a crosswalk mapping fields from the MARC (Machine-Readable Cataloging) format to the MODS (Metadata Object Description Schema) and Dublin Core metadata schemas. It lists MARC codes and fields from the S100 digitized course book data along with their corresponding MODS and DC elements. The crosswalk is intended to help transform MARC metadata from the S100 records into MODS and Dublin Core for the Open University Digital Library Project from 2012.