> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-specifications/snomed-ct-release-file-specification/snomed-ct-identifiers/6.5-partition-identifier.md).

# Partition Identifier

The penultimate two-digits of the [SCTID](/snomed-ct-specifications/snomed-ct-release-file-specification/appendices/appendix-b.-specification-reference-information/s/sctid-data-type.md) (second and third from the right), are the partition identifier.

The partition identifier indicates the nature of the component identified. This allows the identifier of a description to be distinguished from the identifier of a concept.

The partition identifier also indicates whether the SCTID contains a namespace identifier (*long format*) or follows the *short format* applicable to identifiers of components that originated in the International Release. Identifiers of components that originated in the International Release of SNOMED CT have one of the following partition identifier values:

**Partition identifier Values for Short Format SCTIDs**

| PartitionId | Component type |
| ----------- | -------------- |
| 00          | Concept        |
| 01          | Description    |
| 02          | Relationship   |

***

Identifiers of components that originated in an extension have one of the following partition identifier values:

**Partition identifier Values for Long Format SCTIDs**

| PartitionId | Component type             |
| ----------- | -------------------------- |
| 10          | Concept                    |
| 11          | Description                |
| 12          | Relationship               |
| 16          | Postcoordinated Expression |

***

All other partition identifier values are reserved for future use.

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