The classes and their definitions appearing within the NHS data standards meta data model are listed in alphabetical order.

Each listed class contains a 'Description' tab that link to its nationally agreed definition, an 'Attributes' tab that links to a list of its attributes and a 'Relationship' tab that links to a list of its relationships it has with other classes.

The 'Where Used' tab provides a list of all the diagrams that the class is included in. Each diagram is a sub-set of the meta data model but does not contain an exclusive set of classes. Thus the same class can appear in more than one diagram.

Each attribute name or class name which appears in the definition text, attribute list or relationships is in uppercase. Where the name also appears in blue indicates that it is clickable and if clicked on will display the definition for that class or attribute.

The following information may be shown against a class attribute:

Keys The unique identifier of a class may include one or more attributes. These are known as key attributes and are shown with 'K' before the attribute name. Attributes are sequenced with the key attributes first.

The following information is shown for each class relationship:

Keys The unique identifier of a class may include one or more relationships to other classes. These are indicated by 'K' before the relationship description. Relationships are sequenced with the key relationships first.
Description The nature of the relationship is indicated by 'must be' if the relationship is mandatory and by 'may be' if the relationship is optional.
 Where relationships from one class to others are mutually exclusive, then 'or' appears at the beginning of the description between the second and subsequent exclusive relationships. Mutually exclusive relationships are shown on diagrams by a short straight line cutting across the relationship.

The classes, attributes and relationships are logical model components. The classes are comprised of attributes and the Attribute 'tab' is the way of displaying these. An attribute can only belong to one class (although the Where Used 'tab' will show every class or other object where it is referenced). The relationships identify any optional links or mandatory dependencies between classes. The relationship 'tab' is the way of displaying the relationships associated with a class.