Order of the source plot for "Combine time-series" in derived time series?

Confirming an intuition suggested by the UI: when configuring a Combine time-series card in the derived time-series UI, I can specify multiple source plots, and specify the “first” or “last” to perform an union.

The order is specified by the order in the right hand side ? So here, the “red” (H) timeseries will take precedence (if present) over the green time-series (I). Correct ?

Yes, that’s correct. The red will take precedence with the first operation and green with last.