diff --git a/doc/implementation.tex b/doc/implementation.tex
index 52955e4..629e989 100644
--- a/doc/implementation.tex
+++ b/doc/implementation.tex
@@ -457,7 +457,7 @@ TODO
 
 \chapter{Text and Graphics Display}
 
-TODO: Textbuf, pixelbuf, draw order
+TODO: Textbuf, pixelbuf, graphics mode, chart of the draw order
 
 \section{Text Buffer}
 
@@ -789,6 +789,7 @@ TODO
 \namespaceis{Graphics}{graphics}
 
 \begin{outline}
+\1\formalsynopsis{TODO}{to be added.}
 \end{outline}