Index: libcfa/src/iostream.cfa
===================================================================
--- libcfa/src/iostream.cfa	(revision 0050a5ff3fdf8bc520652ac831418c77148183f4)
+++ libcfa/src/iostream.cfa	(revision 17a1b2182301e39b5769acd3251de92e8c34df40)
@@ -10,6 +10,6 @@
 // Created On       : Wed May 27 17:56:53 2015
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Mon Dec 24 18:33:40 2018
-// Update Count     : 589
+// Last Modified On : Mon Mar  4 20:57:24 2019
+// Update Count     : 593
 //
 
@@ -27,4 +27,22 @@
 
 forall( dtype ostype | ostream( ostype ) ) {
+	ostype & ?|?( ostype & os, zero_t ) {
+		if ( sepPrt( os ) ) fmt( os, "%s", sepGetCur( os ) );
+		fmt( os, "%d", 0n );
+		return os;
+	} // ?|?
+	void ?|?( ostype & os, zero_t z ) {
+		(ostype &)(os | z); nl( os );
+	} // ?|?
+
+	ostype & ?|?( ostype & os, one_t ) {
+		if ( sepPrt( os ) ) fmt( os, "%s", sepGetCur( os ) );
+		fmt( os, "%d", 1n );
+		return os;
+	} // ?|?
+	void ?|?( ostype & os, one_t o ) {
+		(ostype &)(os | o); nl( os );
+	} // ?|?
+
 	ostype & ?|?( ostype & os, bool b ) {
 		if ( sepPrt( os ) ) fmt( os, "%s", sepGetCur( os ) );
Index: libcfa/src/iostream.hfa
===================================================================
--- libcfa/src/iostream.hfa	(revision 0050a5ff3fdf8bc520652ac831418c77148183f4)
+++ libcfa/src/iostream.hfa	(revision 17a1b2182301e39b5769acd3251de92e8c34df40)
@@ -10,6 +10,6 @@
 // Created On       : Wed May 27 17:56:53 2015
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Mon Dec 24 18:33:40 2018
-// Update Count     : 220
+// Last Modified On : Tue Feb 26 16:57:22 2019
+// Update Count     : 221
 //
 
@@ -62,4 +62,9 @@
 
 forall( dtype ostype | ostream( ostype ) ) {
+	ostype & ?|?( ostype &, zero_t );
+	void ?|?( ostype &, zero_t );
+	ostype & ?|?( ostype &, one_t );
+	void ?|?( ostype &, one_t );
+
 	ostype & ?|?( ostype &, bool );
 	void ?|?( ostype &, bool );
Index: tests/.expect/io1.txt
===================================================================
--- tests/.expect/io1.txt	(revision 0050a5ff3fdf8bc520652ac831418c77148183f4)
+++ tests/.expect/io1.txt	(revision 17a1b2182301e39b5769acd3251de92e8c34df40)
@@ -1,6 +1,6 @@
 9 6 28 0 7 1 2
-1 2 3
-123
-123
+0 1 2 3
+0123
+0123
 
 opening delimiters
Index: tests/io1.cfa
===================================================================
--- tests/io1.cfa	(revision 0050a5ff3fdf8bc520652ac831418c77148183f4)
+++ tests/io1.cfa	(revision 17a1b2182301e39b5769acd3251de92e8c34df40)
@@ -10,6 +10,6 @@
 // Created On       : Wed Mar  2 16:56:02 2016
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Fri Dec 21 16:02:55 2018
-// Update Count     : 114
+// Last Modified On : Mon Mar  4 21:42:47 2019
+// Update Count     : 115
 //
 
@@ -19,7 +19,7 @@
 	int x = 3, y = 5, z = 7;
 	sout | x * 3 | y + 1 | z << 2 | x == y | (x | y) | (x || y) | (x > z ? 1 : 2);
-	sout | 1 | 2 | 3;
-	sout | '1' | '2' | '3';
-	sout | 1 | "" | 2 | "" | 3;
+	sout | 0 | 1 | 2 | 3;
+	sout | '0' | '1' | '2' | '3';
+	sout | 0 | "" | 1 | "" | 2 | "" | 3;
 	sout | nl;