The SLK is derived by joining the ‘letters of name’ (2nd, 3rd and 5th letters of the family name, and 2nd and 3rd letters of the first given name), ‘date of birth’, and ‘sex’ to create a 14 character identifier. There are also some instances where the SLK SLK information may be unknown, and substitute characters are used instead. The format of the key is XXXXXDDMMYYYYN where: • XXXXX is the 2nd, 3rd and 5th letters of the family name and the 2nd and 3rd letters of the first name. For example: John Smith becomes ‘MIHOH’ • DDMMYYYY is the Patient’s Date of Birth • N is the Patient’s Sex, where 1 = Male and 2 = Female Non Alphabetic Characters such as spaces and hyphens (“-“) are ignored. If a name is too short to extract a character, a 2 is substituted for this character. If a patient is missing a family name or has a single name only, 999 is substituted for the family name component |