I want to know the answer to the following question:
How many separate classification systems do agencies in England and Wales use?
All the background I'm provided with is that "Comparability of the information being recorded by officers was brought into question by the Office for National Statistics (ONS) in September 2007, as part of its Equality Data Review; one problem cited was the number of reports that contained an ethnicity of "Not Stated."". Is that enough to answer the question?