[3][4] IC codes refer to a police officer's visual assessment of the ethnicity of a person, and are used in the quick transmission of basic visual information, such as over radio.
[4] They differ from self-defined ethnicity (SDE, or "18+1") codes, which refer to how a person describes their own ethnicity.
[4] When recording a person's details (such as in the case of a stop and search or arrest), police are required to ask for and use SDE categories where possible, even if the category chosen does not match the officer's own assessment.
[4] IC codes have been used to record individuals' ethnicities in the Police National Computer.
[4][5] They have also been used in the reports on ethnicity in the criminal justice system published annually as required by the Criminal Justice Act 1991,[6][2] and in some scientific research.