After speaking to a string rep and asking about tension (this is not a maker that provides tension numbers) the word that was used that stuck in my head was 'proprietary.' Now when any manufacturer of anything says info is proprietary it is because they believe knowledge of said info could lead to competitors gaining insight into their product in one way or another. Ergo my theory is now that many of these string makers fear revealing tension data would allow someone to reverse engineer their 'proprietary' core/wrap ratios (D'Addario's tension .pdf explains tension and unit weight, etc) and we all know how they sometimes go on and on about their carefully tested and specially chosen core/wrap ratios. I wonder if it has been that concern all along keeping tension data out of consumers' reach, not as much a fear of revealing imbalanced sets as letting other makers in on their secret sauce recipe for the core/wrap mojo. Maybe D'Addario figured long ago that since they made so many strings for others in the market that sharing their proprietary info would not hurt them in a way it might hurt someone else who is going it alone or starting up from scratch, hence they were for the only big maker to reveal that data for a long time. Anyhow... Carry on!