diff --git a/README.md b/README.md
index 09a83c3..3a97d34 100644
--- a/README.md
+++ b/README.md
@@ -39,5 +39,8 @@ Thank You
 TODO
 ----
 
+* verify NTAG213 data to be a Sonicare brush head (check NDEF contents and MFG regex?)
+  * NDEF might point to different Philips URLs - see https://forum.dangerousthings.com/t/weirdest-nfc-device-ive-seen/11430/3
 * determine brush head type from [data](https://blog.mbirth.uk/2026/03/29/sonicare-brush-head-nfc-data.html)
-* allow writing other data (different type)
+* allow writing other data (different type, different settings, different timestamp)
+  * to test: 1B:pp:pp:pp:pp,A2:gg:dd:dd:dd:dd (p=password, g=page, d=data)