The UK Data Service is implementing a generic, three tier access policy. The three tiers are:
These categories are generic because they combine modes of access and conditions of use, and there are likely to be overlaps and differences between the three major categories.
Open data and safeguarded data are legally 'not personal' according to the relevant legislation, e.g. Data Protection Act and Statistics and Registration Services Act.
The difference between 'open' and 'safeguarded' is that safeguarded data may have a residual risk of disclosure, and open data do not.
Controlled data are data which can be defined as personal.