The classification process is done according a quantitative and qualitative assessment of two parameters: the consistency (C) of the observation and the residual strangeness (E) after investigation.

• Strangeness (E): This is the measure of the residual strangeness after comparison with known phenomena hypotheses.
• Consistency (C): This is the product of the quantity and  the reliability of the data submitted and collected during the investigation. The objectivity of this data is weighted according to a specific table, part of the GEIPAN methodology.

Classification categories:

• Classification A: Phenomenon perfectly identified after investigation.
• Classification B: Phenomenon probably identified after investigation.
• Classification C: Phenomenon not identified due to lack of data or information.
• Classification D: Phenomenon not identified after investigation.

A revisit process, or a new analysis, of cases C and D may be conducted if new information related to these cases is communicated to GEIPAN after the initial investigation.