Self defined ethnicity

Self defined ethnicity 'codes' are a set of codes used by the Home Office in the United Kingdom to classify an individual's ethnicity according to that person's self-definition.

Codes

The codes are also called "18 + 1" codes, as there are 18 of them, plus one code for "not stated". In addition to the previously used 16+1 codes, they contain the categories W3 and O2, while A4 is now replacing O1.
The code system originated in the 2001 United Kingdom census based on Recommendation 61 of the Stephen Lawrence Inquiry Report (SLIR).
British police forces are required to use the SDE 18+1 codes when spoken contact has taken place and an individual has been given an opportunity to state their self-perceived ethnicity.

List of SDE codes

;WhiteW1 - BritishW2 - IrishW3 - Gypsy or Irish TravellerW9 - [Other White (people)|White (classification of ethnicity in the United Kingdom)|Any other White background]
;Mixed or Multiple ethnic groupsM1 - White and Black CaribbeanM2 - White and Black AfricanM3 - White and AsianM9 - Any other Mixed or Multiple background
;Asian or Asian BritishA1 - IndianA2 - PakistaniA3 - BangladeshiA4 - ChineseA9 - Any other Asian background
;Black, Black British, Caribbean or AfricanB1 - CaribbeanB2 - AfricanB9 - Any other Black, Black British or Caribbean background
;Other ethnic groupsO2 - ArabO9 - Any other ethnic group
;Not statedNS - Not Stated.