What to do with stuff that will be needed, but you're not sure when?
I received an email about a software patch. When I looked into it, I discovered that it does not affect anyone in the company NOW, but may need to be applied later whenever we upgrade another software package that I'm not responsible for. I don't have any estimates of when the other software will be upgraded, but eventually (maybe within the next 2 years) it will happen.
So what do I do with this email? Tickler file may bring it to my attention too early (causing me to re-encounter the patch email repeatedly) or too late (when it will only be helpful if I'm dedicating some brain RAM to remember that it's in some future folder, which is anti-GTD). I'm not responsible for the other software, so nothing will really spur me to look for this in my reference files once it gets upgraded. I don't think I trust the people who ARE responsible for the other software to remember or document this patch.
So what do I do with this thing?