diff --git a/siibra/attr/util/region_mapping/v0.1.json b/siibra/attr/util/region_mapping/v0.1.json
index 47142c9..40cf13a 100644
--- a/siibra/attr/util/region_mapping/v0.1.json
+++ b/siibra/attr/util/region_mapping/v0.1.json
@@ -76,6 +76,9 @@
                 },
                 {
                     "$ref": "#/definitions/row-index"
+                },
+                {
+                    "$ref": "#/definitions/col-index"
                 }
             ]
         },
@@ -138,6 +141,17 @@
                     "type": "number"
                 }
             }
+        },
+        "col-index": {
+            "type": "object",
+            "properties": {
+                "@type": {
+                    "const": "csv/col-index"
+                },
+                "index": {
+                    "type": "number"
+                }
+            }
         }
     }
 }
\ No newline at end of file