For term_exists, “no” should not include every uncertainty. Just “very” uncertain or similar. More than moderate uncertainty.
Term temporal should include past and present but not future. Or at least acknowledge that you are combining two concepts, time and actuality (future may or may not happen, like rule out pneumonia may or may not be true, or patient may develop seizures). I think future is really a form of conditional. If patient does keep appointment, then it will be HIV clinic.
Value is up to you guys. I can see both arguments for codes vs text. I guess the argument for coded is that it's the only way anyone will be able to use it across sites. And if it can't be used across sites then don't bother to separate it from the others. I think I just convinced myself.
I lean towards putting other modifiers as a string in the same table. Otherwise waste time coding things no one will use across the network.
Need to remind people that term exists = “no” is not negation. Could in theory have three levels, positive, negative, and indeterminate where negative has to be negated with no other conflicting modifiers. Or keep it simple: exists and indeterminate.