diff --git a/README.md b/README.md
index 2a3d24b..5d77688 100644
--- a/README.md
+++ b/README.md
@@ -56,7 +56,7 @@ AAAB_C.D
 - **AAA** is the 3 digits index of the file in the PZZ starting at 000.
 - **B** describe the compression state of the file when packed in the PZZ. If compressed it's **C** and if not it's **U**.
 - **C** is the name of the PZZ.
-- **D** is the extension of the file. If the file is compressed it's **.pzzp** and if the file is uncompressed by default it's **.dat**
+- **D** is the extension of the file. If the file is compressed it's **.pzzp** (PZZ Part) and if the file is uncompressed by default it's **.dat**
 
 For example file **012C_cmn_data.dat** describe :
 - the 13th file off the pzz,