An ID definition is a description of an identifier for the elements of one or more element types.
In order to be able to guarantee the identification of an element, criteria must be defined that make an element unique. The criteria, the key properties, refer to the properties of an element type. The key properties are used to persistently administer elements in the workspace.
Tools that return elements or element lists must return all the key property values of the element as a minimum. An element cannot be created without the availability of all the key property values.