DDLm dictionary version 4.1.0

_type.purpose

Name:
_type.purpose

Definition:

   
    The primary purpose or function the defined data item serves in a
    dictionary or a specific data instance.

Type: Code

The data value must be one of the following:

Import >>> Applied ONLY in the DDLm Reference Dictionary <<< Used to type the SPECIAL attribute "_import.get" that is present in dictionaries to instigate the importation of external dictionary definitions.

Method >>> Applied ONLY in the DDLm Reference Dictionary <<< Used to type the attribute "_method.expression" that is present in dictionary definitions to provide the text method expressing the defined item in terms of other defined items.

Audit >>> Applied ONLY in the DDLm Reference Dictionary <<< Used to type attributes employed to record the audit definition information (creation date, update version and cross reference codes) of items, categories and files.

Identify >>> Applied ONLY in the DDLm Reference Dictionary <<< Used to type attributes that identify an item tag (or part thereof) or external location.

Describe Used to type items with values that are descriptive text intended for human interpretation.

Encode Used to type items with values that are text or codes that are formatted to be machine parsable.

State Used to type items with values that are restricted to codes present in their "enumeration_set.state" lists.

Key Used to type an item with a value that is unique within the looped list of these items, and does not contain encoded information.

Link Used to type an item that acts as a foreign key between two categories. The definition of the item must additionally contain the attribute "_name.linked_item_id" specifying the data name of the item with unique values in the linked category. The values of the defined item are drawn from the set of values in the referenced item. Cross referencing items from the same category is allowed.

Composite Used to type items with value strings composed of separate parts. These will usually need to be separated and parsed for complete interpretation and application.

Number Used to type items that are numerical and exact (i.e. no standard uncertainty value).

Measurand Used to type an item with a numerically estimated value that has been recorded by measurement or derivation. A data item definition for the standard uncertainty (SU) of this item must be provided in a separate definition with _type.purpose of 'SU'. The value of a measurand item should be accompanied by a value of its associated SU item, either: 1) integrated with the measurand value in a manner characteristic of the data format; or 2) as a separate, explicit value for the associated SU item. These alternatives are semantically equivalent.

`SU`	Used to type an item with a numerical value that is the standard uncertainty of another data item. The definition of an SU item must include the attribute "_name.linked_item_id" which explicitly identifies the associated measurand item. SU values must be non-negative.

Internal Used to type items that serve only internal purposes of the dictionary in which they appear. The particular purpose served is not defined by this state.

Enumeration default: Describe

Category:
type

		contents
		indexes
		sample pages
		purchase
		CIF dictionaries

Crystallographic Information Framework

DDLm dictionary version 4.1.0

_type.purpose

International Tables for Crystallography

Volume G: Definition and exchange of crystallographic data

Edited by S. R. Hall and B. McMahon

IUCrData