# Concept help - Data Element Derivation

A Data Element Derivation describes a standardised rule or equation that transforms a set of input Data Elements to produce a set of output Data Elements. application of a derivation rule to one or more input

A data element derivation is a formal description of how a particular Data Element can be calculated based on the values of other data elements.

For example, a data element describing a Person-Body Mass Index, BMI Value can be derived from the data elements Person-Weight, Kg and Person-Height, cm according to the derivation rule BMI = Weight/Height2.

ISO/IEC 11179-3 Section 11.5.2.6

Data_Element_Derivation is a class each instance of which models a data element derivation (3.2.33), the application of a derivation rule (3.2.45) to one or more input data elements (3.2.28) to derive one or more output data elements.

Data_Element_Derivation is a class that associates the Data_Element(s) (11.5.2.1) that serve as sources or inputs with a Derivation_Rule (11.5.2.5) and the Data_Element(s) that are the products or outputs of the Derivation_Rule.

ISO/IEC 11179-3 Section 11.5.2.5

Derivation_Rule is a class each instance of which models a derivation rule (3.2.45), logical, mathematical, and/or other operations specifying derivation. The Derivation_Rule may range from a simple operation such as subtraction to a very complex set of derivations (derivation being defined as a relationship between a Derivation_Rule and an input set upon which it acts). Derivation_Rules are not limited to arithmetic and logical operations.

A Derivation_Rule may have a derivation_rule_application association with zero or more application Data_Element_Derivations, where the Derivation_Rule provides the rule for the associated Data_Element_Derivation.

A Derivation_Rule may be registered as a Registered_Item without necessarily being associated with any Data_Element_Derivation. As a Registered_Item, a Derivation_Rule is directly or indirectly associated with an Administration_Record and can be identified, named, defined and optionally classified as a Classifiable_Item in a Classification_Scheme.

Every Derivation_Rule must have exactly one derivation_rule_specification of type Text that specifies the rule semantics.

Every Derivation_Rule must have exactly one derivation_rule_notation of type Notation that specifies the syntax and semantics used in the derivation_rule_specification.

## Fields available on this metadata type

Field ISO definition
Name The primary name used for human identification purposes.
Definition Representation of a concept by a descriptive statement which serves to differentiate it from related concepts. (3.2.39)
Version Unique version identifier of this metadata item.
References Significant documents that contributed to the development of the metadata item which were not the direct source for the metadata content.
Origin The source (e.g. document, project, discipline or model) for the item (8.1.2.2.3.5)