INTRODUCTION This Standard supersedes RS-209 and RS-209-1. It includes all items prepared by JEDEC Committee JT-8 on Mechanical Standardization@ and approved by the Electronic Industries Association up to April 1962. It should be noted that this Standard differs from previous issues in that reference letters are used on the diagrams instead of numerals. The dimensions@ both inch and metric@ are given in tabulated form. The metric conversion used is according to that proposed by the International Organization for Standardization (ISO) . Basis : 1 in. = 25.4 mm. (exactly). Unless otherwise noted@ the metric dimensions are derived from the original inch dimensions.