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+## Register new datatype
+
+This example shows how to register a new dataType/dataValue in Semantic MediaWiki.
+
+* [Datatype](https://www.semantic-mediawiki.org/wiki/Help:Datatype)
+* [DataValue](https://www.semantic-mediawiki.org/wiki/Help:DataValue)
+
+### Type registration
+
+All IDs must start with an underscore, two underscores indicate a truly internal
+(non user-interacted type), three underscores should be used by an extension.
+
+`TypesRegistry::getDataTypeList` expects that the following information are provided:
+
+* A type id (e.g. `FooValue::TYPE_ID`)
+* An associated class
+* An item type (storage type)
+* A declaration whether it is a subData type (e.g subobject) or not
+* Whether a type is browsable or not
+
+<pre>
+return array(
+	// ...
+	FooValue::TYPE_ID => [ FooValue::class, DataItem::TYPE_WIKIPAGE, false, false ],
+);
+</pre>
+
+<pre>
+class FooValue extends DataValue {
+
+	/**
+	 * DV identifier
+	 */
+	const TYPE_ID = '_foo';
+
+	/**
+	 * @see DataValue::parseUserValue
+	 *
+	 * @param string $value
+	 */
+	protected function parseUserValue( $userValue ) {
+		...
+	}
+
+}
+</pre>
+
+### Label registration
+
+By default, DataTypes (Date, URL etc.) are registered with a corresponding property
+of the same name to match the expected semantics. For an exemption, see
+`smwgDataTypePropertyExemptionList`.
+
+Find `i18n/extra/en.json` and extend the canonical description (which is English) with something like:
+
+<pre>
+	"dataTypeLabels":{
+		"_foo": "SomeType"
+		...
+	},
+	"dataTypeAliases":{
+		"SomeType": "_foo"
+		"ExtraAlias": "_foo"
+		...
+	},
+</pre>