--- /dev/null
+/*\r
+ * SExpr.java\r
+ *\r
+ * Copyright 1997 Massachusetts Institute of Technology.\r
+ * All Rights Reserved.\r
+ *\r
+ * Author: Ora Lassila\r
+ *\r
+ * $Id: SExpr.java,v 1.1 2010/06/15 12:27:50 smhuang Exp $\r
+ */\r
+\r
+package org.w3c.tools.sexpr;\r
+\r
+import java.io.PrintStream;\r
+\r
+/**\r
+ * Interface for all new s-expression subtypes.\r
+ */\r
+public interface SExpr {\r
+\r
+ /**\r
+ * Print a representation of the s-expression into the output stream.\r
+ */\r
+ public void printExpr(PrintStream out);\r
+\r
+}\r