diff --git a/doc/implementation_notes.md b/doc/implementation_notes.md
index b3856598bd30f7f0b59f3126b839507adaf3bd28..60e9081277407a812dd34398b529c4119c5e2762 100644
--- a/doc/implementation_notes.md
+++ b/doc/implementation_notes.md
@@ -1,6 +1,14 @@
 Implementation notes
 ====================
 
+Lightweight cleaning mode
+-------------------------
+
+Due to *popular* request, MAT2 is providing a *lightweight* cleaning mode,
+that only cleans the superficial metadata of your file, but not
+the ones that might be in **embeded** resources. Like for example,
+images in a PDF or an office document.
+
 Symlink attacks
 ---------------