diff --git a/journal/2021-04-09.md b/journal/2021-04-09.md
index b3893e700..2da9c4e21 100644
--- a/journal/2021-04-09.md
+++ b/journal/2021-04-09.md
@@ -1,3 +1,6 @@
 # 2021-04-09
 
-- til about the [[therigata]] from a comment in https://news.ycombinator.com/item?id=26729986
\ No newline at end of file
+- til about the [[therigata]] from a comment in https://news.ycombinator.com/item?id=26729986
+- [[invisible xml]] was surfaced by [[codex]]
+  - [[treedoc]]
+  - [[tree notation]]
\ No newline at end of file