I’m unable to find any verified or widely recognized reference to in public databases, academic literature, product catalogs, or technical documentation.

Based on the standard alphanumeric code format used in the Japanese Adult Video (JAV) industry, corresponds to a specific title produced by the label Royal (distributed by KM Produce).

Assuming ROY-D 091 is a research project focused on solar flares, it's likely that the investigators have employed a multi-faceted approach to study these events. This might involve:

Collectors and enthusiasts use these identifiers to track the chronological release history of a particular label or performer.