Hi,
For Graham & Dodd the Margin of Safety is the difference between the intrinsic value (fundamental value justified by facts) and the market value. Intrinsic and market values are equal only through coincidence. G&D assumed that the appropriate margin of safety for investments is 30-50%. Intrinsic value is whichever is greater of Net Adjusted Asset Value and Earnings Power Value. Another way of viewing intrinsic value is Net Adjusted Asset Value plus the Franchise Value.