Correct mapping of variables to IPCC categories

[danielhuppmann]

While doing some clean-up of historical emissions timeseries, I was wondering whether the description for the variable "Emissions|CO2|AFOLU" is correct - the current description (copied from NAVIGATE) mentions only IPCC category 3, but if I understand it correctly, this should actually be the sum of IPCC categories 3 and 4.

common-definitions/definitions/variable/emissions/emissions.yaml

Line 14 in 836c3fe

- Emissions|{Level-2 Species}|AFOLU:

By extension, "Emissions|CO2|AFOLU|Agriculture" should (closely) match IPCC category 3 and "Emissions|CO2|AFOLU|Land" should match IPCC category 4.

Or am I misinterpreting the variable structure?
Please advise @IAMconsortium/common-definitions-emissions