Codelist

Overview

An SDMX Codelist is a managed list of classification codes.

Structure Properties

Structure Type	Standard SDMX Structural Metadata Artefact
Maintainable	Yes
Identifiable	Yes
Item Scheme	Yes
SDMX Information Model Versions	1.0, 2.0, 2.1
Concept ID	CODELIST

Context within the SDMX 2.1 Information Model

The schematic illustrates the core artefacts of the SDMX 2.1 Information Model, and how Codelists and Codes fit in.

Codelists can be referenced directly by Data Structure Definitions (DSD), or indirectly through Concepts to explictly define the set of legal values for enumerated Dimensions or Attributes.

Usage

SDMX Codelists are lists of classification codes used principally for defining the set of allowed values for enumerated Components in Data Structure Definitions (DSDs) or Metadata Structure Definitions which describe Reference Metadata.

Each code is a separate Item so must have an ID and a Name, but can also have an optional Description. While Code IDs must be unique within a Codelist, the same Code ID may be safely used in other Codelists. For instance: The code 'A' may be used in a Frequency Codelist to represent 'Annual', but also appear in an Industry Codelist to represent 'Agriculture'.

Flat Codelists

Flat Codelists are simple lists of codes with no explicit or implied relationships or hierarchies.

Example: CL_FREQUENCY Codelist

Code ID	Code Name
A	Annual
S	Half-yearly, semester
Q	Quarterly
M	Monthly
W	Weekly
D	Daily
B	Daily - Business Week
N	Minutely

Codelists with Simple Hierarchies

SDMX allows simple hierarchies to be defined within flat Codelists by making a code the parent of codes that logically sit under it in the hierarchy.

Imagine a CL_REF_AREA Codelist containing individual codes for each European country, and a code (EUR) for Europe as a whole. A simple hierarchy for Europe can be created by setting EUR as the parent for each of the countries:

Code ID	Code Name	Parent
EUR	Europe	(none)
DE	Germany	EUR
FR	France	EUR
IT	Italy	EUR
GR	Greece	EUR
SE	Sweden	EUR
AU	Austria	EUR
PL	Poland	EUR

Other than acting as a parent, EUR behaves as a normal code allowing series for EUR or any of the individual contries.

A Code can only have one parent meaning that it can only appear once in a simple Codelist hierarchy. This may be restrictive where Codes can be logically organised into multiple different groups. In the CL_REF_AREA example, countries could also be grouped into trading blocs in addition to geographical regions.

SDMX Hierarchical Codelists should be used where Codelists have more complex hierarchical structures.

Hierarchical Codelists

SDMX Hierarchical Codelists are separately maintainable artefacts used to describe complex Code hierarchies.

Conventions

'CL_' Codelist ID Prefix

Codelist IDs are given a 'CL_' prefix to distinguish them from other structures. For instance: CL_FREQ, CL_REF_AREA, CL_AGE.

Code ID Conventions

Codes can take any legal SDMX ID. But there are several conventions that should be taken into account when choosing Code IDs:

Uppercase Code IDs	By convention, Code ID's are in uppercase such as 'ABC'. Lower case Codes are valid (for example 'abc'), but care should be taken in their use to avoid confusion.
'_Z' Code	The '_Z' code is conventionally used for the Undefined and Unknown classification.
'TOTAL' Code	The 'TOTAL' code represents the total or sum of the dimension. For a 'country' dimension, series with TOTAL would indicate the sum of observation values for all countries.

Examples

Simple Flat Codelist

Code ID	Code Name
A	Annual
S	Half-yearly, semester
Q	Quarterly
M	Monthly
W	Weekly
D	Daily
B	Daily - Business Week
N	Minutely

Flat Codelist with Optional Code Descriptions

Code ID	Code Name	Code Description
K	Calendar component	Synonyms: Calendar effects; calendar factors
X	Seasonal component	Synonyms: Seasonal effects; seasonal factors
M	Seasonal and calendar components	Synonyms: Seasonal and calendar effects; seasonal and calendar factors
I	Irregular component	Synonym: Irregular effects
N	Neither seasonally adjusted nor calendar adjusted data	Synonyms: Raw data; unadjusted data