Question: I wanted to highlight a particular chord of my [previous question](https://music.stackexchange.com/q/114106/77758) because it was bugging me a bit. What would you call a dominant triad over a subdominant bass, in pop/jazz roman numeral analysis? It could be seen as a `V7` in third inversion, but if you have a strong subdominant bass it doesn't really sound like it. But just calling it a `IV` seems... meh. Especially because we call the inverse, a subdominant triad over a dominant bass, a sus chord.

**Update**: Thanks all for your responses. As most of you have said, roman numeral analysis isn’t really suited for these kinds of chords. I might decide to just slash chords for bass and then come up with a different way to notate secondary chords and modulations in a functional manner. I don’t want to do this literally because that doesn’t make sense in a tonic-agnostic notation.

[![Sample](https://i.stack.imgur.com/MbtNF.png)](https://i.stack.imgur.com/MbtNF.png)

Answer: 
Not fully understanding the dots - it's key C,from the key sig., and the chords go from F to G7 back to F.

That G7 is in 3rd inversion, because the F is in the bass.If it was going to be called V/IV, in key C, that would make it C7, which it obviously isn't, and anyway C7 would be designated I7.

RN isn't particularly helpful in cases such as this. It could be called G/F, which again isn't helpful fot transcription to other keys.

A better way would be to label using NNS - the Nashville Number System.
Normally the melody do-ti-la above IV (the subdominant) will be considered (the middle not e) as passing tone. Now together with parallels of 3rd and 6th we get a resoti (V) chord. I think it is most useful to consider this passage as a slash chord and it will help you to transpose it easily in other keys.

I think the idea of passing tones or suspensions 6-5;9-8;11-10 is more logical than the 3rd inversion of V7.