The variable column

The ‘variable’ column of the IAMC format describes the type of information represented in the specific timeseries. The variable name implements a “semi-hierarchical” structure using the | character (pipe, not l or i) to indicate the structure or “depth”. Names (should) follow a structure like Category|Subcategory|Specification.

Semi-hierarchical means that a hierarchy can be imposed, e.g., one can enforce that the sum of Emissions|CO2|Energy and Emissions|CO2|Other must be equal to Emissions|CO2 (if there are no other Emissions|CO2|… variables).

However, this is not mandatory, e.g., the sum of Primary Energy|Coal, Primary Energy|Gas and Primary Energy|Fossil should not be equal to Primary Energy because this would double-count fossil fuels.

Variable naming conventions

A variable name should adhere to the following conventions:

  • A | (pipe) character indicates levels of hierarchy.

  • Do not use spaces before and after the | character, but add a space between words

    Primary Energy|Non-Biomass Renewables
  • Do not use abbreviations (e.g, PHEV) unless strictly necessary.

  • Do not use abbreviations of statistical operations (min, max, avg) but always spell out the term.

  • All words must be capitalised (except for and, w/, w/o, etc.).

  • If necessary to add a method or operation-identifier (e.g., Share, per capita) to a variable name, add it in square brackets, e.g.,

    Population|Urban [Share]


The unit attribute is required and its value should be compatible with the iam-units package. Alternatively, a variable can be dimensionless, i.e., not have a unit.