The Common Reporting Format (CRF) tables use a number of standard notation keys. These keys are specified in the text of the UNFCCC Reporting Guidelines. The most frequently used notation keys in the CRF and repeated in the analysis documents based on the CRF can be easily confused. The definitions of each is given below:

• “NO” (not occurring) for activities or processes in a particular source or sink category that do not occur within a country

• “NE” (not estimated) for existing emissions by sources and removals by sinks of greenhouse gases which have not been estimated. Where “NE” is used in an inventory for emissions or removals of CO₂, N₂O, CH₄, HFCs, PFCs, or SF₆, the Party should indicate in both the NIR and the CRF completeness table why emissions or removals have not been estimated

• “NA” (not applicable) for activities in a given source/sink category that do not result in emissions or removals of a specific gas. If categories in the CRF for which “NA” is applicable are shaded, they do not need to be filled in

• “IE” (included elsewhere) for emissions by sources and removals by sinks of greenhouse gases estimated but included elsewhere in the inventory instead of the expected source/sink category. Where “IE” is used in an inventory, the Party should indicate, using the CRF completeness table, where in the inventory the emissions or removals from the displaced source/sink category have been included and the Party should explain such a deviation from the expected category

• “C” (confidential) for emissions by sources and removals by sinks of greenhouse gases which could lead to the disclosure of confidential information