One of my several current engagements is within public transit.
Usually we talk about party master data and product master data as the most common domains of master data and sometimes we add places (locations) as the third domain in a P trinity of “parties, products and places” or perhaps a W trinity of “who, what and where”.
The when dimension, the times where events are taking place, is most often seen as belonging to the transaction side of life in the databases.
However in public transit you certainly also have timetables as an important master data domain. The service provided by a public transit authority or operator is described as belonging to a certain timeframe where a given combination of services is valid. An example is the “Summer Schedule 2011”.
An other industry with a time depending master data domain I have seen is education, where the given services (lessons) usually are described as belonging to a semester.
Wonder if you have met other master data types that is more belonging to the “when” domain than the “who, what and where” domains? Did you have any problems with the timeliness of times?