This report describes the methods, developed by the American Institute of Physics in cooperation with Engineering Index, Inc., by which both organizations could reduce costs by eliminating duplication of keyboarding and indexing. The three sets of problems that confronted the interchange of their data bases (classification and indexing, formats, data elements, and special characters) are noted, and the means by which they were resolved are explained. Included in the report are three tables that present a comparative study of special characters used by the two data bases, a data element identification log, and data element descriptions. A final section describes the format conversion for tape exchanges between AIP and Ei. Appended are the processor flowchart, the AIP-Ei converter fowchart, the Physics and Astronomy Classification Scheme (PACS) to Subject Headings for the Engineering (SHE) mapping table, the PACS optics supplement, and a description of the conversion of AIP-Ei indexing for optics. (JD)