In the metals testing field, I have worked with BS, CSA, EN, DIN, ISO, JIS, TUV and about 10 other international standards organization's documents. I have also worked with ASME BPVC, ASTM, DOT, SAE AMS, AS, MAM and many others in the U.S. One caution that I have regarding a matrix of "equivalent" documents is that they are not equivalent. For example in specifying a metal alloy, the primary element percentages may be the same, but the allowed trace elements levels are not. The Charpy impact test specified by ASTM E 23 is similar to the DIN metals impact test, however the anvil, weights, and methods of calibration are entirely different. In tensile testing of metals, you can convert the yield and ultimate strength values, however the strain rates between the U.S. standards and the European standards are different, thus the values cannot be directly compared. For fasteners like bolts and nuts, you can covert the size, but the grades of fasteners are not equivalent.
My recommendation is that if you are supplying materials to a standard, such as BS, DIN, EN, ISO, you need to purchase that document. People complain about the cost of standards in the U.S., but you will find that the European standards are typically much higher in cost. I once bought a 3 page standard that cost $200, and that was about 8 years ago. I also bought (for the company I worked for) a three ring binder of German pressure vessel standards, with about 100 pages in it for over $800.
Wes R.