an Entity references as follows:
The NRS social grades are a system of demographic classification used in the United Kingdom. They were originally developed by the National Readership Survey (NRS) to classify readers, but are now used by many other organisations for wider applications and have become a standard for market research. They were developed in the late 1950s and refined in following years and achieved widespread usage in 20th century Britain. Their definition is now maintained by the Market Research Society.