I use soft pencil and erase things that are done, moved to another list or no longer relevant. If I don't have time to erase, I put a check (done!) or an X (no longer needed) or a slash (moved elsewhere) next to them so I'll know I can ignore them for now and erase them later. Eventually the paper will get worn out from too many erasures but the notebook I'm using seems to have really good paper that can be erased many times; and I try not to press too hard when writing. Thick, soft paper is good, I think.
I used to have a system that each week I would re-write one context list onto a new page, applying the two-minute rule and deleting or removing anything I didn't want to keep on the list. That way I didn't have to keep working with two pages at once, which didn't work well for me.
I write the more important or urgent things further to the left, and the things that will require more time and/or energy closer to the top of the page, similarly to what I describe here: http://woodgold.wordpress.com/2011/0...-required-etc/
Inability is an abstract thing involving comparison with alternate universes; it cannot be experienced.