diff --git a/src/components/download.js b/src/components/download.js
index cbfdbc0..d0ce83b 100644
--- a/src/components/download.js
+++ b/src/components/download.js
@@ -1,3 +1,7 @@
+// adapted from the DOM.download method as per this issue:
+
+// https://github.com/observablehq/framework/issues/906
+
 const xmlns = "http://www.w3.org/2000/xmlns/";
 const xlinkns = "http://www.w3.org/1999/xlink";
 const svgns = "http://www.w3.org/2000/svg";