diff --git a/_specifications/lsp/3.18/language/callHierarchy.md b/_specifications/lsp/3.18/language/callHierarchy.md
index 6567d119b..61dcd08ab 100644
--- a/_specifications/lsp/3.18/language/callHierarchy.md
+++ b/_specifications/lsp/3.18/language/callHierarchy.md
@@ -69,6 +69,19 @@ _Response_:
 <div class="anchorHolder"><a href="#callHierarchyItem" name="callHierarchyItem" class="linkableAnchor"></a></div>
 
 ```typescript
+export namespace ReferenceTag {
+	/**
+	 * Statement with r-value usage of the referenced variable.
+	 */
+	export const Read = 1;
+	/**
+	 * Statement with l-value usage of the referenced variable.
+	 */
+	export const Write = 2;
+}
+
+export type ReferenceTag = 1 | 2;
+
 export interface CallHierarchyItem {
 	/**
 	 * The name of this item.
@@ -85,6 +98,11 @@ export interface CallHierarchyItem {
 	 */
 	tags?: SymbolTag[];
 
+	/**
+	 * Reference tags of this item.
+	 */
+	referenceTags?: ReferenceTag[];
+
 	/**
 	 * More detail for this item, e.g. the signature of a function.
 	 */