It categorises goods by tariff code into three categories based on their risk level. The following guidance https://www.gov.uk/government/publications/risk-categories-for-animal-and-animal-product-imports-to-great-britain

A summary of the different documents required and arrival checks is provided in the following table.

RISK LEVELLOWMEDIUMHIGH
IPAFFSYYY
HEALTH CERTIFICATENYY
ENTRY VIA BCPY
(30th April onwards)
YY
ROUTINE CHECKSOCCASIONALPOTENTIALROUTINE