# Comma usage in a complex series

I have the following caption title:

Fig. 5. Measured small-signal gain, input return loss, and output return loss vs. frequency of C-band HPA.

This is equivalent to (a), (b), and (c) vs. (d)

Question

Ambiguity lies in the above as to whether (a), (b), and (c) are all versus (d) or whether it is simply a list of three things. Pleas help with the correct use of punctuation to illustrate the former case.

• Won't the answer be obvious from the graph? Commented May 14, 2014 at 2:35
• Although this question may have an answer, you can probably do better than relying on punctuation to make your meaning clear.
– user28567
Commented May 14, 2014 at 2:48
• Snailboat - feel free to expand upon exactly how I can do better please. Commented May 14, 2014 at 3:29
• Erik Kowal - it may be the case, but what would you do if there wasn't a graph? Commented May 14, 2014 at 3:31
• If it's a graph, the captions is correct, go ahead. If not, and you suspect any ambiguity, please elaborate why.
– Kris
Commented May 14, 2014 at 5:43

I would reverse the order:

Fig. 5. Frequency of C-band HPA versus measured small-signal gain, input return loss, and output return loss.

There is still a slight opportunity for ambiguity but this form is much more likely to associate the entire list as being compared to the "frequency of C-band HPA."

Could you just stick in an all as you have used in your explanation of how it could be misinterpreted?

This is equivalent to (a), (b) and (c) all vs. (d)

If you really have to, you can use an extra set of parentheses or square brackets to make it unmistakably clear. You might also label the two entities you're comparing:

``````This is equivalent to figures (a), (b), and (c) vs. figure (d).
``````