diff --git a/content/notes/24-protection-of-file-systems.md b/content/notes/24-protection-of-file-systems.md
index bf02ea0a4..6c67d2103 100644
--- a/content/notes/24-protection-of-file-systems.md
+++ b/content/notes/24-protection-of-file-systems.md
@@ -6,4 +6,22 @@ tags:
 - lectures
 ---
 
+# protection model
+file system shared by many users
+- users should be able to keep them private
 
+need to define
+- mechanisms
+- policies
+
+types of file access users can have
+- read
+	- includes list
+- write
+	- includes delete	
+- execute
+	- if a directory is not executable you cannot get into it (run it) 
+
+# Access control bits
+
+# access control models
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