diff --git a/src/lib/data_structures/table_of_contents.ts b/src/lib/data_structures/table_of_contents.ts
new file mode 100644
index 0000000..8bf447f
--- /dev/null
+++ b/src/lib/data_structures/table_of_contents.ts
@@ -0,0 +1,6 @@
+export interface TocEntry {
+  title: string;
+  href: string;
+  expanded: boolean;
+  children: Array<TocEntry> | null;
+}