My broker uses $VIX.X for "CBOE Volatility Index S&P500". The other symbol you provides appears to be limited to the 3 months-out contract.
The VIX is the measurement of volatility over the next 30 days.
VXV is the measurement of volatility over the next 3 months.
Using a ratio between the two allows me to measure how much contango or backwardation is occurring. At least, theoretically.
Yes, different quote services require the use of different special characters. For some reason, VIX is was easily found, but for some reason VXV was not easily found. I know it exists, because I searched it and found it 2 weeks ago. I just couldn't find it now.
After screwing around online for the better part of a week, I finally found the answer:
"the ticker symbol for the Cboe 3-Month Volatility Index was changed from “VXV” to “VIX3M”"
For some reason, Yahoo Finance isn't taking the transition very well. Under "^VXV" it's showing all the historical data on the Cboe 3-Month Volatility Index, but not the current price. Under ^VIX3M it's showing the current price, but not the historical data. TD appears to be even more confused.
"
Le sigh"
At least I got my answer. Now trying to dig to find my information . . . .