When making the vinaigrette are the ounces weight or volume?

Mea culpa. I didn't scroll far enough down to see the vinaigrette. Note to self: drink more coffee before attempting to answer questions.

Yes, liquid ounces is the correct answer. But you can ignore that anyway. Vinaigrette is based on ratio; classic recipe is three parts oil to one part vinegar. You can reduce the amount of oil if you prefer a stronger vinegar taste. You will also need to whisk in a bit of mustard as an emulsifying agent.

I can't imagine they'd use weight ounces when measuring liquids for a dressing. It has to be fluid ounces.

I'm a bit puzzled over how ounces could be measured as volume. If you really want to be exact, get out your kitchen scale, put a bowl on top, tare to zero and then put in enough greens to reach six ounces. But in a salad, you don't have to be right on the nose with amounts. Just grab four handfuls, and you wil be fine. If you are thinking of the ounce measures on a measuring cup, those are for liquids, I believe. I never use those--a scale will provide a more accurate reading for various ingredients.