diff --git a/scans/README.md b/scans/README.md
index 06ef363..6e2d782 100644
--- a/scans/README.md
+++ b/scans/README.md
@@ -30,7 +30,7 @@ Details of the files:
 * trysys.s: page 65  of 01-s1.pdf
 * scope.cas: pages 3-18 of 03-scope.pdf
 * cas.s: pages 1-8 of 04-cas.pdf
-* cas.x: pages 9-17 of 04-cas.pdf
+* cas.cas: pages 9-17 of 04-cas.pdf
 * adm.s: pages 2-11  of 05-1-4.pdf
 * ald.s: pages 13-17 of 05-1-4.pdf
 * apr.s: pages 19-30 of 05-1-4.pdf
diff --git a/scans/cas.x b/scans/cas.cas
similarity index 95%
rename from scans/cas.x
rename to scans/cas.cas
index 3779a83..b3fd662 100644
--- a/scans/cas.x
+++ b/scans/cas.cas
@@ -433,68 +433,6 @@ gc
 ia
 ma
 ml "???
-"** 04-cas.pdf page 16
-mc
-mi
-kk
-hk
-fi
-fc
-ha
-x
-mn
-r
-
-:c7
-x
-aa
-v
-ak
-nb
-x
-mn
-r
-
-:c8
-x
-gc
-v
-ea
-ca
-ac
-ai
-ck
-ek
-gi
-gc
-ia
-ka
-mc
-mi
-kk
-ik
-gi
-x
-mn
-r
-
-:c9
-x
-ka
-v
-mc
-mi
-kk
-ck
-ai
-ac
-ca
-fa
-hc
-hi
-fk
-x
-mn
 "** 04-cas.pdf page 17
 x
 mn
@@ -557,8 +495,66 @@ ai
 ac
 ca
 ka
+"** 04-cas.pdf page 16
+mc
+mi
+kk
+hk
+fi
+fc
+ha
+x
+mn
+r
 
-" The end of file seems abrupt, every other :cX section ends with:
-" x
-" mn
-" r
+:c7
+x
+aa
+v
+ak
+nb
+x
+mn
+r
+
+:c8
+x
+gc
+v
+ea
+ca
+ac
+ai
+ck
+ek
+gi
+gc
+ia
+ka
+mc
+mi
+kk
+ik
+gi
+x
+mn
+r
+
+:c9
+x
+ka
+v
+mc
+mi
+kk
+ck
+ai
+ac
+ca
+fa
+hc
+hi
+fk
+x
+mn
+r
diff --git a/src/cmd/cas.x b/src/cmd/cas.cas
similarity index 100%
rename from src/cmd/cas.x
rename to src/cmd/cas.cas