Suggesting transport variables and tags

[yiyi1991]

This PR proposes new transport sector tags and variables for the NGFS project (Phase VI) but also generally. Key points:

• Add new tag transport mode (Road, Rail, Active, etc.) in addition to the current vehicle-type tag (bus, truck, ldv, etc., which only sit in the subcategory of Road) and tag drive-type (BEV, ICE, etc.), so that mode shift can be presented clearly in the energy service variables.
• By default, Aviation and Shipping do not include bunkers now.
  • the previous Domestic Aviation and Domestic Shipping are not precise for activities within model regions, especially in global models
• Two-wheelers are separated from a subcategory of LDV and rescoped as 2W and 3W.

TODO

• Technical issues still remain in energy service variable namings (being able to match with how they are named in NAVIGATE, how they are defined in SDG indicators)

How to review:

• Read the files changed or generate nomenclature export-definitions . definitions.xlsx
• Do the new transport variables (especially mode-tag-related) make sense to you? (defination clear? variables exclusive?)

[RahelMA]

Thank you for adding these important variables for the transport sector. I was wondering if we could also include the following variables for the JUSTMip project:

Energy Service|Transport|Pass|Road|LDV|Four Wheelers 
Energy Service|Transport|Pass|Road|LDV|Three Wheelers 
Energy Service|Transport|Pass|Road|LDV|Two Wheelers 
Energy Service|Transport|Pass|Domestic Aviation 
Energy Service|Transport|Pass|Non-motorized|Cycle
Energy Service|Transport|Pass|Non-motorized|Walk 
Energy Service|Transport|Pass|Non-motorized 
Energy Service|Transport|Bunkers|Pass 

[yiyi1991]

Dear Rahel, thanks.

Energy service variables should indeed be included though I would prefer using/improving the tag sets proposed by this PR (e.g., Non-motorized -> Active, no four wheelers, "domestic aviation" does not make sense to global models as "domestic" becomes "within model region" there, Passenger|Bunkers instead of Bunkers|Passenger, etc.).

Does JUSTMip have an approaching deadline? Feel free to contribute to this PR and pin me to check/review, or kindly consider the tags proposed in this PR and open another to JUSTMip workflow only.