It was suggested to add the word "Raw value: …" or similar to tooltips in the tabular result browser. This is most relevant on BCE dates, where the internal, "raw" value is different from the rendered date.

The tooltips are the main communication tool to teach the users that there is a difference between the internal ISO date and the rendering. In ISO -0000 means "1 BCE", -0001 means "2 BCE" and so on. The tooltip could even explain that and say "Raw ISO timestamp: …" and avoid the word "date" entirely.