diff --git a/ncdump/cdl4/ref_tst_nul3.cdl b/ncdump/cdl4/ref_tst_nul3.cdl
new file mode 100644
index 000000000..32d6dda5d
--- /dev/null
+++ b/ncdump/cdl4/ref_tst_nul3.cdl
@@ -0,0 +1,15 @@
+netcdf ref_tst_nul3 {
+dimensions:
+	n = 8 ;
+variables:
+	char cdata(n) ;
+	char c;
+
+// global attributes:
+		:global = "x\000y" ;
+data:
+
+ cdata = "abc\000def" ;
+
+ c = "";
+}
diff --git a/ncdump/cdl4/ref_tst_nul4.cdl b/ncdump/cdl4/ref_tst_nul4.cdl
new file mode 100644
index 000000000..3af071fbd
--- /dev/null
+++ b/ncdump/cdl4/ref_tst_nul4.cdl
@@ -0,0 +1,18 @@
+netcdf ref_tst_nul4 {
+dimensions:
+	n = 8 ;
+variables:
+//	char cdata(n) ;
+	string sdata ;
+//	char c ;
+
+// global attributes:
+//		string :global = "x\000y";
+data:
+
+// cdata = "abc\000def" ;
+
+ sdata = "123\0004" ;
+
+// c = "" ;
+}