Data element name
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A data element name is a name given to a data element in, for example, a data dictionary or metadata registry. In a formal data dictionary, there is often a requirement that no two data elements may have the same name, to allow the data element name to become an identifier, though some data dictionaries may provide ways to qualify the name in some way, for example by the application system or other context in which it occurs.
In a database driven data dictionary, the fully qualified data element name may become the primary key, or an alternate key, of a Data Elements table of the data dictionary.
The data element name typically conforms to ISO/IEC 11179 metadata registry naming conventions and has at least three parts:
- Object, Property and Representation term.
Many standards require the use of Upper camel case to differentiate the components of a data element name. This is the standard used by ebXML, GJXDM and the NIEM.
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[edit] Example of ISO/IEC 11179 naming in relational databases
ISO/IEC 11179 is applicable when naming tables and columns within a relational database.
Tables are Collections of Entities, and follow Collection naming guidelines. Ideally, a collective name is used: eg., Personnel. Plural is also correct: Employees. Incorrect names include: Employee, tblEmployee, and EmployeeTable.
Columns are Properties of the Entity and are named in a multi-part format:
[Object] [Qualifier] Property RepresentationTerm
The Object part may be omitted from a name when the property is within its object's context. The Qualifier is used when it is necessary to uniquely identify an element. For example, columns on the Work_Orders table would be expressed as:
WorkOrder_Number Requirements_Text Requesting_Employee_Number Approving_Employee_Number
For Requirements_Text, the full name (i.e., the name that goes in the registry, or data dictionary) is WorkOrder_Requirements_Text; the Object part is omitted because it is declared in the WorkOrders table.
The Requesting_Employee_Number and Approving_Employee_Number columns have Qualifiers to ensure that the data element names are unique and descriptive. The Object part of the element name is also omitted because it is declared within the object context.
Note that for the examples provided, an underscore was used as a separator. A separator is not mandated by ISO/IEC 11179 but is recommended.
[edit] Example of ISO/IEC 11179 name in XML
Users frequently encounter ISO/IEC 11179 when they are exposed to XML Data Element names that have a multi-part Camel Case format:
Object [Qualifier] Property RepresentationTerm
The specification also includes normative documentation in appendices.
For example the XML element for a person's given (first) name would be expressed as:
<PersonGivenName>John</PersonGivenName>
Where Person is the Object=Person, Property=Given and Representation term="Name". In this case the optional qualifier is not used.
