Classification fields

Classifications are represented as records presented in a hierarchical fashion. If the type of a field is Classification, a record in the Classification hierarchy can be chosen as the value of the field. The general purpose way of handling hierarchies is described in "Hierarchies".

You can allow a Classification field's value to be chosen from any record in the Classification hierarchy. A Classification field can be defined that may contain any record shown in this hierarchy.

Usually, a field is restricted to some part of the hierarchy. For example, a field might be restricted to the classification Discipline, which includes everything under Discipline, such as Civil, Electrical, and Electrical Lighting.

Classifications like the ones under Discipline are useful simply for their name and what their name implies to people. Because classifications are represented by records, they can have additional fields that contain data used to determine the outcome of computations. For example, a classification that indicates what type of equipment something is may have a field whose value is the phone number to call if the equipment needs repair.

The List data type is sometimes a good alternative to Classification. There is a comparison of the two types in "Lists versus classifications".