How to report Tiers

[FlorianLeblancDr]

Hi @IAMconsortium/common-definitions-coordination

This is more a tutorial than an issue regarding the reporting of tiers,
as following our last meeting our first assignment was to provide a list of Tier 1 variables for each subgroup.

After discussing with Daniel, tier should simply be reported as an attribute, as in the following:

- GDP|MER:
    definition: GDP converted to USD at market exchange rate (MER)
    unit: billion USD_2010/yr
    tier: 1

The example provided in https://github.com/danielhuppmann/common-definitions/tree/main/definitions/variable/emissions
For emission, is misleading, as tags are defined for tiers, which does not really define tiers for the variable, in the sens usually understood for variable in templates.

Best,

Florian

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Edit: the emission variable example has been fixed by @danielhuppmann in #65 , renaming "Tier" in "Level" in variable names

[realxinzhao]

For the emission example
They can simply add tier attributes to the main emissions.yaml file for different values to fix this, right?