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0580 Data Dictionaries

At the start of a data project, it is often necessary to describe the types of data that is needed. This is called a data specification.
DataField entities are used to model specific data fields required by the data project. As the project progresses, data schemas are defined to describe how data is organized in the different data assets used by the project.

The data dictionary maintains lists of pre-defined, reusable data fields.

UML

ObjectIdentifier classification

The ObjectIdentifier classification indicated that a data item is typically used as a unique identifier.

DataDictionary classification

Identifies that a collection is an organized collection of defined data fields that can be used in a data specification to describe some desired data.

DataSpec classification

Identifies that this is a collection that describes the data requirements for a project or initiative.

DataStructure entity

A referenceable that provides list of data fields that describe the structure of a data source.

  • displayName - Name of the data structure.
  • namespace - Optional namespace to help build a qualified name for the data structure.
  • description - Description of the data field.
  • versionIdentifier - Managed version identifier.

DataField entity

A referenceable that describes a data field. It is used to specify/validate the values in an asset's schema, which in turn describes the structure of data in the digital resource.

  • displayName - Name of the data field.
  • namespace - Optional namespace to help build a qualified name for the data field.
  • aliases - Alternative name to use for the data field - useful when matching against a schema.
  • namePatterns - List of patterns to use to match a name against a schema attribute - useful when matching against a schema.
  • description - Description of the data field.
  • isDeprecated - Is this data field deprecated?
  • versionIdentifier - Managed version identifier.
  • defaultValue - Default value to use if the actual data value is null.
  • isNullable - Can the data field store null?
  • dataType - What is the data type of this field
  • minimumLength - What is the minimum length of this field - typically used with string fields.
  • length - What is the length (in bytes) table up by this field.
  • precision - How many digits after the decimal point.
  • orderedValues - Are the values sorted
  • sortOrder - DataItemSortOrder value identifying the sort direction used on the data field values.
  • namePatterns - Regular expressions that characterize the name of the data field.

MemberDataField relationship

Represents an association between a data structure and one of its data fields.

DataStructureDefinition relationship

Represents an association between a data structure that describes a data source and a certification type that indicates that certified elements conform to the data structure and associated definitions (such as glossary term and data class).

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