Retrospection = true for entities means that the lifespan of the entity consists of one or more time intervals. A single customer may not have a single, continuous lifespan. It is also true of other entities such as the wine dimension. A wine may be available for intervals of time spanning many years, or the entire lifespan may be punctuated by periods when the wine is not available. An example of this would be the Beaujolais Nouveau, which, for some reason, is very popular when first available in November each year but must be consumed quickly, as it soon deteriorates. As this wine is not available for 10 months out of each year, it is reasonable to say that the lifespan of this wine is discontinuous.
Retrospection = true for entities means that the lifespan of the entity consists of one or more time intervals. A single customer may not have a single, continuous lifespan. It is also true of other entities such as the wine dimension. A wine may be available for intervals of time spanning many years, or the entire lifespan may be punctuated by periods when the wine is not available. An example of this would be the Beaujolais Nouveau, which, for some reason, is very popular when first available in November each year but must be consumed quickly, as it soon deteriorates. As this wine is not available for 10 months out of each year, it is reasonable to say that the lifespan of this wine is discontinuous.