The database was moved from card index files to computer in 1982. A lot of the original data were still in existence until fairly recently, causing problems due to the constraints imposed by 1980's technology (eg null fields full of asterisks). These data have now been cleaned and the constraints removed. All new data entered use a comprehensive set of rules to ensure accuracy and allow flexibility. For example, new subscribers will be asked for date of birth rather than age, as well as telephone number and any e-mail address. Whenever anyone talks to a subscriber, the current details are checked and reconfirmed. As the organisation is entirely dependent on the data they are forced to keep revisiting the data integrity.