In addition to the typical calculation metadata, Digichem also assigns a unique ID to each calculation result. These IDs are calculated from the checksum of the corresponding log file, meaning they are deterministic, and are used to prevent an identical calculation from being inserted into the same database twice. In addition, each calculation has a `history` attribute, which can optionally contain the ID of the calculation that occurred before it and thus generated the geometry for the following calculation. For example, the `history` attribute of an excited-states calculation might contain the ID of the geometry optimisation that preceded it. In this way, the researcher can easily determine the chain of calculations that lead to each result.