Thanks LiveOak, I will try this today...
Now am I correct that with this scheme, the value list will not "update itself" when someone adds a new items.
What I have is a list of vendors of services that's already pretty long. Every time someone adds a new project, they may ...
a) Pick vendors from the list that already exists
: Pick some of the vendors from the existing list, and also add new ones
c) Add only new vendors to the list.
...so I think that what you suggest will work for the first option but not for the second and third?
I have been using the 'other' option for this value list so far.
Anyway I'll experiment with what you suggest - thanks for taking the time to outline it to me.