maybe: n/a to project association, related info with the n/a and one-offs?
There are a couple of issues here: none of this is really GTD, but a few hints that work for me. Form must follow function--do what works for you .
I often have to indicate on my action lists what project the action goes with, so I use an abbreviation. Don't over think this if you are a basic person. If you are more of a genius type I imagine you could use something like the Dewey Decimal system.
The action lists are basically a list of actions based on the projects you intend to move forward within a time frame of something, probably your weekly review, or before you close your summer house, or whatever. Some projects however have a different time frame, so I will put the deadline in along with the short name for the project. Sometimes, also in dealing with " waiting fors" or agenda items, it is also useful to have the date that you initiated communication about the item and when you reminded. In entering all this info you must weigh the cost of that time and thinking against the cost of looking back at your support materials.
Sometimes it saves time to have the action after the next action in parenthesis waiting as a reminder, such as get approval from Smith for budget for church (photocopy, distribute, refile under Smith and church). In this case, Smith is someone who is likely to call you at a random time and ask you what you did in last meeting with him.)
Now here is something different
ne-offs. Unless you have a team of assistants, there are probably dozens of single items actions you need to do. Maybe they belong on a checklist in a perfect world or maybe that's too much overhead. And, gasp, maybe they could be one-offs (get coffee and and if time permits, do grocery shopping; fertilize plants on window sill and if time permits pluck dead leaves). I would put the one-poffs and one-off pluses on the list in a manner that designates differently from the n/as that support defined projects. Once they are done, they are done. No need to reconnect to your support materials
Now, my unsolved problem is with the independent actions that support my projects--if I use paper, I can see if I have crossed them if I keep the papers and have the time to search tmy lists. If I use the Palm, I can't seem to find an easy way to see what I have done if I have checked them as done.