Jihoon Min

Thanks @danielhuppmann. I attach an xlsx here since it doesn't allow csv.. With the dataframe given below, what I tested was `data.filter(region="World").stack_plot()`, while this `data.filter(region="World").line_plot()` is working fine. [debugdata_stackplot.xlsx](https://github.com/IAMconsortium/pyam/files/3891993/debugdata_stackplot.xlsx)

> Thanks. I'm puzzled why there is no "mixed units discarded" log message for fix_cost (for fom) and var_cost (for vom). > > Next, for each scenario: > > ```python...

From the conversation with @GamzeUnlu95, we've figured out, for case (b) above, all the units are discarded for the three parameters so that they become compatible with each other. But...

> Another workaround could be to use `units/apply/var_cost: ""` in the configuration / YAML file to force var_cost to be dimensionless, to the same effect. A quick question about this...

> I believe that a scenario being optimal with unscaled infeasibilities returns an error for message standalone - @danielhuppmann is this true? If this is the case, then I believe...

The theoretical paper behind this: https://www.sciencedirect.com/science/article/pii/S0360544299000638

> `map_tec_lifetime` is a set created as part of [data_loead.gms](https://github.com/iiasa/message_ix/blob/24934f749f679f80d4d86c47e4b8b69449031dbe/message_ix/model/MESSAGE/data_load.gms#L116). It partly relies on the parameter `technical_lifetime`. The issue is that `technical_lifetime` needs to be defined for all activity years...

I agree with Matt. I think it is no harm to allow users to read those aux results for better debugging. Originally I wanted to read REN.