A model of data integrity

The Clark and Wilson model for expressing data integrity constraints is based upon the principles of segregation of duty and assures the manipulation of data only by well formed transactions. In this paper we propose a model using the Clark and Wilson principes and incorporating an attribute grammar to test if the data has integrity from a user's perspective. The definition that data either has integrity or it fails to have integrity is maintained but a set of qualities of data, e.g., age of the data are allowed to be specified by the data administrator or user. These qualities are used to ascertain whether a datum has met the specified quality.