diff --git a/pmd-plsql/etc/grammar/PldocAST.jjt b/pmd-plsql/etc/grammar/PldocAST.jjt
index 5e030fc847..470147434e 100644
--- a/pmd-plsql/etc/grammar/PldocAST.jjt
+++ b/pmd-plsql/etc/grammar/PldocAST.jjt
@@ -27,6 +27,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 /**
+ * Added ASTIsOfTypeCondition node, added support for USING IN|OUT|IN_OUT
+ * See PMD Bug #1520
+ *
+ * Andreas Dangel 11/2016
+ *====================================================================
  * Adjusted ProgramUnit() to allow Pragma(), even though this is not
  * valid syntax. See PMD Bug #1527.
  *
@@ -1368,7 +1373,7 @@ ASTOpenStatement OpenStatement()  :
 {
 	 <OPEN> [Expression()]
 		//[LOOKAHEAD(functionCall()) functionCall() | QualifiedName()]
-		[<FOR> Expression() [<USING> Expression() ("," Expression())*]] 
+		[<FOR> Expression() [<USING> (<IN> | <OUT> | <IN_OUT>)? Expression() ("," (<IN> | <OUT> | <IN_OUT>)? Expression())*]] 
       { return jjtThis ; }
 }
 
@@ -1967,13 +1972,28 @@ ASTUnaryExpressionNotPlusMinus UnaryExpressionNotPlusMinus() :
   (<NOT>) {sb.append(" NOT "); } 
   (simpleNode = UnaryExpression(false) ) { sb.append(simpleNode.getImage()); }
   |
-   (simpleNode = PrimaryExpression() ) { sb.append(simpleNode.getImage()); }
+   (simpleNode = IsOfTypeCondition() ) {sb.append(simpleNode.getImage()); }
   )
  { 
  jjtThis.setImage(sb.toString()); return jjtThis; 
  }
 }
 
+ASTIsOfTypeCondition IsOfTypeCondition() :
+{ PLSQLNode simpleNode = null; PLSQLNode name = null; StringBuilder sb = new StringBuilder(); }
+{
+  (
+    LOOKAHEAD(<IDENTIFIER> <IS>)
+    ((name = Name()) {sb.append(name.getImage());} <IS> {sb.append(" IS");} [<NOT> {sb.append(" NOT");}] <OF> {sb.append(" OF");} [<TYPE>]
+      "(" [<ONLY>] Name() ("," [<ONLY>] Name() )* ")")
+  |
+    (simpleNode = PrimaryExpression() ) { sb.append(simpleNode.getImage()); }
+  )
+  {
+    jjtThis.setImage(sb.toString()); return jjtThis;
+  }
+}
+
 /**
  * 2006-05-23 - Matthias Hendler - Added lookahead otherwise warning encountered.
  *                                 Warning arised while adding methode triggerUnit(). 
@@ -3248,6 +3268,7 @@ TOKEN [IGNORE_CASE]:
  *                                 Added: <MERGE: "MERGE">, <AFTER: "AFTER">, <BEFORE: "BEFORE">,
  *                                 <INSTEADOF: "INSTEAD OF">, <FOREACHROW: "FOR EACH ROW">, <REFERENCING: "REFERENCING">,
  *                                 <OLD: "OLD">, <PARENT: "PARENT">
+ * 2016-11-04 - Andreas Dangel - Added <ONLY: "ONLY">, <IN_OUT: "IN_OUT">
  */
 
 TOKEN [IGNORE_CASE]:
@@ -3347,6 +3368,7 @@ TOKEN [IGNORE_CASE]:
 <IF: "IF"> |
 <IMMEDIATE: "IMMEDIATE"> |
 <IN: "IN"> |
+<IN_OUT: "IN_OUT"> |
 <INDEX: "INDEX"> |
 <INDICES: "INDICES"> |
 <INCLUDING: "INCLUDING"> |
@@ -3408,6 +3430,7 @@ TOKEN [IGNORE_CASE]:
 <OF: "OF"> |
 <OID: "OID"> |
 <ON: "ON"> |
+<ONLY: "ONLY"> |
 <OPAQUE: "OPAQUE"> |
 <OPEN: "OPEN"> |
 <OPERATOR: "OPERATOR"> |
diff --git a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/ast/PLSQLParserVisitorAdapter.java b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/ast/PLSQLParserVisitorAdapter.java
index 87dda81911..470156e3e3 100644
--- a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/ast/PLSQLParserVisitorAdapter.java
+++ b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/ast/PLSQLParserVisitorAdapter.java
@@ -690,4 +690,8 @@ public class PLSQLParserVisitorAdapter implements PLSQLParserVisitor {
                 return visit((PLSQLNode) node, data);
         }
 
+    @Override
+    public Object visit(ASTIsOfTypeCondition node, Object data) {
+        return visit((PLSQLNode) node, data);
+    }
 }
diff --git a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/rule/AbstractPLSQLRule.java b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/rule/AbstractPLSQLRule.java
index 00951897e1..2260a93e41 100644
--- a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/rule/AbstractPLSQLRule.java
+++ b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/rule/AbstractPLSQLRule.java
@@ -784,6 +784,10 @@ public abstract class AbstractPLSQLRule extends AbstractRule implements PLSQLPar
 	public Object visit(ASTAccessibleByClause node, Object data) {
 		return visit((PLSQLNode) node, data);
 	}
+	@Override
+	public Object visit(ASTIsOfTypeCondition node, Object data) {
+        return visit((PLSQLNode) node, data);
+	}
 
   /*
    * Treat all Executable Code 
diff --git a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/PLSQLParserTest.java b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/PLSQLParserTest.java
index dc11365fb6..df6e983ce1 100644
--- a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/PLSQLParserTest.java
+++ b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/PLSQLParserTest.java
@@ -50,4 +50,14 @@ public class PLSQLParserTest extends AbstractPLSQLParserTst {
     public void testBug1527() throws Exception {
         parsePLSQL(IOUtils.toString(PLSQLParserTest.class.getResourceAsStream("ast/InlinePragmaProcError.pls")));
     }
+
+    @Test
+    public void testBug1520IsOfType() throws Exception {
+        parsePLSQL(IOUtils.toString(PLSQLParserTest.class.getResourceAsStream("ast/IsOfType.pls")));
+    }
+
+    @Test
+    public void testBug1520Using() throws Exception {
+        parsePLSQL(IOUtils.toString(PLSQLParserTest.class.getResourceAsStream("ast/Using.pls")));
+    }
 }
diff --git a/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/IsOfType.pls b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/IsOfType.pls
new file mode 100644
index 0000000000..c536a73f45
--- /dev/null
+++ b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/IsOfType.pls
@@ -0,0 +1,23 @@
+PROCEDURE IsOfType (
+inChannelID IN number,
+inOperID IN number,
+inClientId IN number,
+ioFPOobj IN FPO_OBJ,
+inPackageIDout IN number,
+inStatusId IN number)
+is
+loFPOGE_OBJ FPOGE_OBJ;
+BEGIN
+
+IF ioFPOobj IS OF (FPOGE_OBJ) THEN
+loFPOGE_OBJ:=treat(ioFPOobj AS FPOGE_OBJ);
+end if;
+
+IF ioFPOobj IS NOT OF TYPE (ONLY FPOGE_OBJ) THEN
+loFPOGE_OBJ:=treat(ioFPOobj AS FPOGE_OBJ);
+end if;
+
+loFPOGE_OBJ:=SELECT A FROM persons p WHERE IS OF TYPE (employee_t);
+loFPOGE_OBJ:=SELECT A FROM persons p WHERE IS NOT OF TYPE (ONLY employee_t, other_t);
+
+end;
\ No newline at end of file
diff --git a/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Using.pls b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Using.pls
new file mode 100644
index 0000000000..3eaf1734f7
--- /dev/null
+++ b/pmd-plsql/src/test/resources/net/sourceforge/pmd/lang/plsql/ast/Using.pls
@@ -0,0 +1,16 @@
+/*
+ * From: https://docs.oracle.com/cd/B13789_01/appdev.101/b10807/13_elems034.htm
+ */
+DECLARE
+   TYPE EmpCurTyp IS REF CURSOR;  -- define weak REF CURSOR type
+   emp_cv   EmpCurTyp;  -- declare cursor variable
+   my_ename VARCHAR2(15);
+   my_sal   NUMBER := 1000;
+BEGIN
+   OPEN emp_cv FOR  -- open cursor variable
+      'SELECT ename, sal FROM emp WHERE sal > :s' USING my_sal;
+   open cursor for 'query' USING variable;
+   open cursor for 'query' USING IN variable;
+   open cursor for 'query' USING OUT variable, IN othervariable;
+   open cursor for 'query' USING IN_OUT variable;
+END;
diff --git a/src/site/markdown/overview/changelog.md b/src/site/markdown/overview/changelog.md
index c6e2439e84..ec693a9b2c 100644
--- a/src/site/markdown/overview/changelog.md
+++ b/src/site/markdown/overview/changelog.md
@@ -41,6 +41,7 @@
 *   java-unusedcode/UnusedModifier
     *   [#1480](https://sourceforge.net/p/pmd/bugs/1480/): false positive on public modifier used with inner interface in enum
 *   PLSQL
+    *   [#1520](https://sourceforge.net/p/pmd/bugs/1520/): \[plsql] Missing PL/SQL language constructs in parser: Is Of Type, Using
     *   [#1527](https://sourceforge.net/p/pmd/bugs/1527/): \[plsql] PRAGMA AUTONOMOUS_TRANSACTION gives processing errors
     *   [#1531](https://sourceforge.net/p/pmd/bugs/1531/): \[plsql] OOM/Endless loop while parsing (PL)SQL
 *   General