For me undoing means deciding your conclusions were wrong. So when you unlink evidence it seems only right to remove the conclusions that describe why you combined them. Others have argued that you shouldwant to keep around the information that you earlier made and unmade decisions, but for me, this is much too subtle and overkill-ish. For me all undo means is that we keep the personas inviolate, so that we can rearrange our evidence into better-reasoned conclusions later. I grant you that I may over-stress the idea that codified evidence should only be in the form of personas, as I don't believe this to be true. But the persona seems to capture so many of our needs that I use it as the central talking point. Thanks for the good words about LifeLines. I can't decide whether to modify it to handle personas or to start from scratch. I'm now in love with developing for the Mac, so I'm pulled in different directions.