Today the 14th January in our times calendar used to be the first day in the new year when the Julian calendar was used before different countries at different times shifted to the Gregorian calendar.
Such shifts in what we generally refer to as reference data is a well-known pain in data management as exemplified in the post called The Country List. Within data warehouse management, we refer to this as Slowly Changing Dimensions.
Master Data Management (MDM) and Reference Data Management (RDM) are two closely related disciplines and often we may use the terms synonymously and indeed sometimes working with the same real world entity is MDM in one context but RDM in another context.
I have worked in industries, as public transit, where the calendar and related data must be treated as master data. But surely, in many other industries this will be an overkill. However, I have seen other entities treated as a simple List of Values (LoV) where it should be handled as master data or at least more complex reference data. Latest example is plants within a global company, where the highest ambition is proposed to be a mark for active or inactive, which hardly reflect the complexity in starting or buying a plant and closing or selling the same and the data management rules according to the changing states.
So happy 14th of January even if this is not New Year to you – but hey, at least it is my birthday.