diff --git a/gradle.properties b/gradle.properties
index b580d70..7235de7 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 group = org.xbib
 name = z3950
-version = 5.0.2
+version = 5.0.3
 
 org.gradle.warning.mode = ALL
diff --git a/z3950-common/src/main/java/org/xbib/z3950/common/operations/SearchOperation.java b/z3950-common/src/main/java/org/xbib/z3950/common/operations/SearchOperation.java
index 10b2d5c..da4c152 100644
--- a/z3950-common/src/main/java/org/xbib/z3950/common/operations/SearchOperation.java
+++ b/z3950-common/src/main/java/org/xbib/z3950/common/operations/SearchOperation.java
@@ -79,9 +79,7 @@ public class SearchOperation extends AbstractOperation<SearchResponse, SearchReq
                 dbs[n].value.value = new ASN1GeneralString(databases.get(n));
             }
             search.databaseNames = dbs;
-            if (logger.isLoggable(Level.FINE)) {
-                logger.log(Level.FINE, search.toString());
-            }
+            logger.log(Level.FINER, search.toString());
             write(search);
             SearchResponse response = read();
             if (response != null) {
diff --git a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Expression.java b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Expression.java
index a77d960..ea5d145 100644
--- a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Expression.java
+++ b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Expression.java
@@ -7,24 +7,37 @@ public class Expression extends Node {
 
     private final String op;
 
-    private final Query q1;
+    private final Query query1;
 
-    private final Query q2;
+    private final Query query2;
 
-    public Expression(String op, Query q1, Query q2) {
+    public Expression(String op, Query query1, Query query2) {
         this.op = op;
-        this.q1 = q1;
-        this.q2 = q2;
+        this.query1 = query1;
+        this.query2 = query2;
     }
 
     @Override
     public void accept(Visitor visitor) {
-        q2.accept(visitor);
-        q1.accept(visitor);
+        query2.accept(visitor);
+        query1.accept(visitor);
         visitor.visit(this);
     }
 
     public String getOperator() {
         return op;
     }
+
+    public Query getQuery1() {
+        return query1;
+    }
+
+    public Query getQuery2() {
+        return query2;
+    }
+
+    @Override
+    public String toString() {
+        return "[Expression: op=" + op + ",query1=" + query1 + ",query2=" + query2 + "]";
+    }
 }
diff --git a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/PQFRPNGenerator.java b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/PQFRPNGenerator.java
index 47b579e..f7ef642 100644
--- a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/PQFRPNGenerator.java
+++ b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/PQFRPNGenerator.java
@@ -47,6 +47,7 @@ public class PQFRPNGenerator implements Visitor {
             if (any instanceof RPNStructure) {
                 rpnQuery.rpn = (RPNStructure) any;
             } else if (any instanceof ASN1OctetString) {
+                // TODO
                 logger.log(Level.INFO, "found ASN1OctetString = " + ((ASN1OctetString) any).get());
             }
             if (pqf.getAttrSet() == null) {
@@ -64,7 +65,13 @@ public class PQFRPNGenerator implements Visitor {
         Operand operand = new Operand();
         operand.attrTerm = new AttributesPlusTerm();
         operand.attrTerm.term = new org.xbib.z3950.common.v3.Term();
-        operand.attrTerm.term.c_general = new ASN1OctetString(query.getTerm().getValue());
+        Term term = query.getTerm();
+        if (term != null) {
+            Logger.getLogger("").log(Level.INFO, "query = " + query + " term = " + term + " value = " + term.getValue());
+            operand.attrTerm.term.c_general = new ASN1OctetString(term.getValue());
+        } else {
+            operand.attrTerm.term.c_null = new ASN1Null();
+        }
         Stack<AttributeElement> attrs = new Stack<>();
         ASN1Any any = !result.isEmpty() && result.peek() instanceof AttributeElement ? result.pop() : null;
         while (any != null) {
@@ -75,9 +82,8 @@ public class PQFRPNGenerator implements Visitor {
         operand.attrTerm.attributes.value = attrs.toArray(new AttributeElement[0]);
         RPNStructure rpn = new RPNStructure();
         rpn.c_op = operand;
-        if (attrs.size() > 0) {
-            result.push(rpn);
-        }
+        Logger.getLogger("").log(Level.INFO, "push rpn = " + rpn);
+        result.push(rpn);
     }
 
     @Override
@@ -95,8 +101,21 @@ public class PQFRPNGenerator implements Visitor {
         if ("@not".equals(op)) {
             rpn.c_rpnRpnOp.s_op.andNotOp = new ASN1Null();
         }
-        rpn.c_rpnRpnOp.s_rpn1 = (RPNStructure) result.pop();
-        rpn.c_rpnRpnOp.s_rpn2 = (RPNStructure) result.pop();
+        ASN1Any rpn1 = result.pop();
+        if (rpn1 instanceof RPNStructure) {
+            Logger.getLogger("test").log(Level.INFO, "rpn1 = " + rpn1);
+            rpn.c_rpnRpnOp.s_rpn1 = (RPNStructure) rpn1;
+        } else {
+            Logger.getLogger("test").log(Level.INFO, "debug rpn1: " + rpn1);
+        }
+        ASN1Any rpn2 = result.pop();
+        if (rpn2 instanceof RPNStructure) {
+            Logger.getLogger("test").log(Level.INFO, "rpn2 = " + rpn2);
+            rpn.c_rpnRpnOp.s_rpn2 = (RPNStructure) rpn2;
+        } else {
+            Logger.getLogger("test").log(Level.INFO, "debug rpn2: " + rpn2);
+        }
+        Logger.getLogger("test").log(Level.INFO, "visit expr: rpn = " + rpn);
         result.push(rpn);
     }
 
@@ -111,6 +130,7 @@ public class PQFRPNGenerator implements Visitor {
 
     @Override
     public void visit(Term term) {
+        Logger.getLogger("test").log(Level.INFO, "push term = " + term);
         result.push(new ASN1OctetString(term.getValue()));
     }
 
diff --git a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Query.java b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Query.java
index 089850f..542710a 100644
--- a/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Query.java
+++ b/z3950-common/src/main/java/org/xbib/z3950/common/pqf/Query.java
@@ -8,11 +8,17 @@ import java.util.LinkedList;
 public class Query extends Node {
 
     private String attrschema;
+
     private final LinkedList<AttrStr> attrspec = new LinkedList<>();
+
     private Query querystruct;
+
     private Setname setname;
+
     private Term term;
+
     private Expression expr;
+
     private PQF pqf;
 
     // ATTR CHARSTRING1 attrstr querystruct
@@ -91,6 +97,9 @@ public class Query extends Node {
 
     @Override
     public String toString() {
+        if (expr != null) {
+            return "[Query: expr=" + expr + "]";
+        }
         return "[Query: term=" + term + " attrschema=" + attrschema + " setname=" + setname +
                 " querystruct=" + querystruct + "]";
     }
diff --git a/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFParserTest.java b/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFParserTest.java
index afcd313..0480eea 100644
--- a/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFParserTest.java
+++ b/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFParserTest.java
@@ -32,7 +32,7 @@ class PQFParserTest {
             }
         }
         assertEquals(errors, 0);
-        assertEquals(ok, 19);
+        assertEquals(ok, 20);
     }
 
     /**
diff --git a/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFTest.java b/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFTest.java
new file mode 100644
index 0000000..66e13c7
--- /dev/null
+++ b/z3950-common/src/test/java/org/xbib/z3950/common/pqf/PQFTest.java
@@ -0,0 +1,39 @@
+package org.xbib.z3950.common.pqf;
+
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.xbib.z3950.common.v3.RPNQuery;
+
+import java.io.StringReader;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+class PQFTest {
+
+    private static final Logger logger = Logger.getLogger(PQFTest.class.getName());
+
+    @Test
+    @Disabled
+    void testParser() throws SyntaxException {
+        String q = "@and @attr 1=4 linux @attr 1=2 sybex";
+        PQFParser parser = new PQFParser(new StringReader(q));
+        parser.parse();
+        PQF pqf = parser.getResult();
+        logger.log(Level.INFO, "pqf = " + pqf.toString());
+    }
+
+
+    @Test
+    void testRPN() {
+        String q = "@and @attr 1=4 linux @attr 1=2 sybex";
+        logger.log(Level.INFO, "rpn = " + createRPNQueryFromPQF(q));
+    }
+
+    private RPNQuery createRPNQueryFromPQF(String query) {
+        PQFRPNGenerator generator = new PQFRPNGenerator();
+        org.xbib.z3950.common.pqf.PQFParser parser = new org.xbib.z3950.common.pqf.PQFParser(new StringReader(query));
+        parser.parse();
+        parser.getResult().accept(generator);
+        return generator.getResult();
+    }
+}
diff --git a/z3950-common/src/test/resources/org/xbib/z3950/common/pqf/pqf-must-succeed b/z3950-common/src/test/resources/org/xbib/z3950/common/pqf/pqf-must-succeed
index b3f3033..0e445ad 100644
--- a/z3950-common/src/test/resources/org/xbib/z3950/common/pqf/pqf-must-succeed
+++ b/z3950-common/src/test/resources/org/xbib/z3950/common/pqf/pqf-must-succeed
@@ -17,3 +17,4 @@ dylan
 @or @and bob dylan @set Result-1
 @attr 4=1 @and @attr 1=1 "bob dylan" @attr 1=4 "slow train coming"
 @and @attr 2=4 @attr gils 1=2038 -114 @attr 2=2 @attr gils 1=2039 -109
+@and @attr 1=4 @attr 2=3 @attr 3=3 @attr 4=1 @attr 5=1 @attr 6=1 "linux" @attr 1=2 @attr 2=3 @attr 3=3 @attr 4=1 @attr 5=1 @attr 6=1 "sybex"