diff --git a/src/util/flat.scad b/src/util/flat.scad
index f7af5b7d..eb8942a1 100644
--- a/src/util/flat.scad
+++ b/src/util/flat.scad
@@ -1,3 +1,13 @@
+/**
+* flat.scad
+*
+* @copyright Justin Lin, 2020
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib2x-flat.html
+*
+**/ 
+
 function flat(lt, depth = 1) =
     depth == 1 ? [for(row = lt) each row] :
                  [for(row = lt) each flat(row, depth - 1)];
\ No newline at end of file