# SCTID Data Type

The [SCTID](https://docs.snomed.org/snomed-ct-specifications/snomed-ct-release-file-specification/appendices/appendix-b.-specification-reference-information/s/sctid-data-type) data type is a 64-bit positive integer.

When rendered as a string an SCTID must always be represented using decimal digits and when rendered as a string has a maximum permitted length of 18 digits and a minimum length of 6 digits.

**Note** : Leading zeros are always omitted from the string rendering of an SCTID. For example the value "101291009" must not be rendered as "0101291009".

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