# Concept help - Data Element Derivation

#### Table of Contents

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 <tt>BMI = Weight/Height^{2}</tt>.

<cite> ISO/IEC 11179-3 Section 11.5.2.6</cite>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.

<cite> ISO/IEC 11179-3 Section 11.5.2.5</cite>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) |

Comments | Descriptive comments about the metadata item (8.1.2.2.3.4) |

Deleted | The date after which the item has been soft deleted and is no longer visible in the registry |

Derivation Rule | text of a specification of a data element Derivation_Rule |

## Official Definition

application of a derivation rule to one or more input Data Elements to derive one or more output data elements. ISO/IEC 11179 - Clause 3.2.33