# Type: XrefString




_A string that is a cross reference to another entity represented in another ontology, vocabulary, database, or website. The string SHOULD be a CURIE or a URL, but this standard relaxes this to a string to support parsing of legacy ontologies that may use other syntaxes. If a CURIE is provided, this SHOULD be registered in a standard registry such as bioregistry._



URI: [xsd:string](http://www.w3.org/2001/XMLSchema#string)

* [base](https://w3id.org/linkml/base): str

* [uri](https://w3id.org/linkml/uri): xsd:string


* [typeof](https://w3id.org/linkml/typeof): string







## See Also

* [https://owlcollab.github.io/oboformat/doc/obo-syntax.html#2.5](https://owlcollab.github.io/oboformat/doc/obo-syntax.html#2.5)

## Identifier and Mapping Information







### Schema Source


* from schema: https://github.com/geneontology/obographs




## Mappings

| Mapping Type | Mapped Value |
| ---  | ---  |
| self | obographs:XrefString |
| native | obographs:XrefString |