description: This is an equivalent of the string on which the extension is sent, but includes additional XHTML markup, such as bold, italics, styles, tables, etc. Existing [restrictions on XHTML content](narrative.html#security) apply. Note that using [markdown](extension-rendering-markdown.html) allows for greater flexibility of display. package_name: hl7.fhir.core derivation: constraint name: String equivalent with html markup type: Extension elements: extension: index: 0 slicing: slices: extension: match: {} schema: {index: 0} max: 0 url: type: uri pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/rendering-xhtml'} index: 1 value: choices: [valueString] index: 3 valueString: {type: string, choiceOf: value, index: 4} package_version: 1.8.0 extensions: extension: {url: null, max: 0, index: 0} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/rendering-xhtml base: http://hl7.org/fhir/StructureDefinition/Extension version: null required: [valueString, value]