diff --git a/raillabel/json_format/object_data.py b/raillabel/json_format/object_data.py
new file mode 100644
index 0000000..78cc13a
--- /dev/null
+++ b/raillabel/json_format/object_data.py
@@ -0,0 +1,22 @@
+# Copyright DB InfraGO AG and contributors
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+from .bbox import JSONBbox
+from .cuboid import JSONCuboid
+from .poly2d import JSONPoly2d
+from .poly3d import JSONPoly3d
+from .vec import JSONVec
+
+
+class JSONObjectData(BaseModel):
+    """Container of annotations of an object in a frame."""
+
+    bbox: list[JSONBbox] | None
+    cuboid: list[JSONCuboid] | None
+    poly2d: list[JSONPoly2d] | None
+    poly3d: list[JSONPoly3d] | None
+    vec: list[JSONVec] | None
diff --git a/raillabel/json_format/poly3d.py b/raillabel/json_format/poly3d.py
index 6c6e15f..488df30 100644
--- a/raillabel/json_format/poly3d.py
+++ b/raillabel/json_format/poly3d.py
@@ -10,7 +10,7 @@
 from .attributes import JSONAttributes
 
 
-class JSONPoly2d(BaseModel):
+class JSONPoly3d(BaseModel):
     """A 3D polyline defined as a sequence of 3D points."""
 
     name: str
diff --git a/raillabel/json_format/vec.py b/raillabel/json_format/vec.py
index 842c00f..925956e 100644
--- a/raillabel/json_format/vec.py
+++ b/raillabel/json_format/vec.py
@@ -11,7 +11,7 @@
 from .attributes import JSONAttributes
 
 
-class JSONPoly2d(BaseModel):
+class JSONVec(BaseModel):
     """A vector (list) of numbers."""
 
     name: str