The standardization of clinical document names is an essential first step towards the optimal use, management, and exchange of documents within and across institutions. The HL7/LOINC Document Ontology (DO) is an existing and evolving document standard developed to provide consistent naming of clinical documents and to guide the creation of LOINC codes for clinical notes. The goal of this study was to explore the feasibility and challenges of mapping local clinical document names from two institutions into the five axes of the DO and then to leverage this mapping for identifying specific LOINC codes. The results indicate that the DO is either adequate or too broad for representing a majority of the document names and that there are LOINC codes available for one- to two-thirds of the names. Through this mapping process, granularity and other issues were revealed that will be valuable for guiding next steps towards effective standardization of clinical document names.