diff --git a/docs/mainframe-design.md b/docs/mainframe-design.md
index 96bfdd9..d0df433 100644
--- a/docs/mainframe-design.md
+++ b/docs/mainframe-design.md
@@ -1,4 +1,4 @@
-## Cardiograph Mark I (mainframe)
+## [DRAFT] Design of the _Cardiograph Mark I_ mainframe computer
 
 The components of a Mark I are: