Data Elements
A data model contains a structured collection of data elements. The structure may be a simple list; it is more likely to be a structure in which data elements are organised into sections or classes.
An individual data element describes a data point that may take a range of different values: e.g., a question on a form, a column in a spreadsheet, or a field in a database.
The range of values allowed for a particular data element is called its value domain. Some value domains may be numeric, with specific units. Some may be enumerated: a list of terms or values, each with a specific interpretation.