Section 1 of this Interpretive Report covers the activities of the Design Division and places them in their proper perspective relative to the state of the art. These activities have been largely concerned with the development of stress analysis techniques based on the theory of elasticity@ and with their experimental verification. It is shown in this report that the significance of the stresses so calculated or measured must be evaluated and that analyses which consider inelastic action must also be used. In the area of pressure vessel heads (section L3)@ methods are now available for the calculation of elastic stresses in any practical shape of head without multiple openings. Experimental verification of the calculations is adequate to give good confidence in their validity. The calculational methods are too laborious for use by the average designer@ but some tables and curves are available for flat@ conical@ hemispherical@ and ellipsoidal heads. The future activities of PVRC should include the preparation of more comprehensive charts or tables for ready use by designers.