diff --git a/libopenfpga/libarchopenfpga/src/pb_type_annotation.cpp b/libopenfpga/libarchopenfpga/src/pb_type_annotation.cpp
index 98fad3dd0..da494f77f 100644
--- a/libopenfpga/libarchopenfpga/src/pb_type_annotation.cpp
+++ b/libopenfpga/libarchopenfpga/src/pb_type_annotation.cpp
@@ -31,7 +31,8 @@ std::vector<std::string> PbTypeAnnotation::operating_parent_mode_names() const {
 }
 
 bool PbTypeAnnotation::is_operating_pb_type() const {
-  return true == operating_pb_type_name_.empty();
+  return (false == operating_pb_type_name_.empty())
+      && (false == physical_pb_type_name_.empty());
 }
 
 
@@ -48,7 +49,8 @@ std::vector<std::string> PbTypeAnnotation::physical_parent_mode_names() const {
 }
 
 bool PbTypeAnnotation::is_physical_pb_type() const {
-  return true == physical_pb_type_name_.empty();
+  return (true == operating_pb_type_name_.empty())
+      && (false == physical_pb_type_name_.empty());
 }
 
 std::string PbTypeAnnotation::physical_mode_name() const {
@@ -75,7 +77,15 @@ int PbTypeAnnotation::physical_pb_type_index_offset() const {
   return physical_pb_type_index_offset_;
 }
 
-BasicPort PbTypeAnnotation::physical_pb_type_ports(const std::string& port_name) const {
+std::vector<std::string> PbTypeAnnotation::port_names() const {
+  std::vector<std::string> keys;
+  for (auto const& element : operating_pb_type_ports_) {
+    keys.push_back(element.first);
+  }
+  return keys;
+}
+
+BasicPort PbTypeAnnotation::physical_pb_type_port(const std::string& port_name) const {
   std::map<std::string, BasicPort>::const_iterator it = operating_pb_type_ports_.find(port_name);
   if (it == operating_pb_type_ports_.end()) {
     /* Return an empty port */
@@ -84,7 +94,7 @@ BasicPort PbTypeAnnotation::physical_pb_type_ports(const std::string& port_name)
   return operating_pb_type_ports_.at(port_name);
 }
 
-int PbTypeAnnotation::physical_pin_rotate_offsets(const std::string& port_name) const {
+int PbTypeAnnotation::physical_pin_rotate_offset(const std::string& port_name) const {
   std::map<std::string, int>::const_iterator it = physical_pin_rotate_offsets_.find(port_name);
   if (it == physical_pin_rotate_offsets_.end()) {
     /* Return a zero offset which is default */
@@ -93,6 +103,14 @@ int PbTypeAnnotation::physical_pin_rotate_offsets(const std::string& port_name)
   return physical_pin_rotate_offsets_.at(port_name);
 }
 
+std::vector<std::string> PbTypeAnnotation::interconnect_names() const {
+  std::vector<std::string> keys;
+  for (auto const& element : interconnect_circuit_model_names_) {
+    keys.push_back(element.first);
+  }
+  return keys;
+}
+
 std::string PbTypeAnnotation::interconnect_circuit_model_name(const std::string& interc_name) const {
   std::map<std::string, std::string>::const_iterator it = interconnect_circuit_model_names_.find(interc_name);
   if (it == interconnect_circuit_model_names_.end()) {
diff --git a/libopenfpga/libarchopenfpga/src/pb_type_annotation.h b/libopenfpga/libarchopenfpga/src/pb_type_annotation.h
index 8849ef273..e03201cde 100644
--- a/libopenfpga/libarchopenfpga/src/pb_type_annotation.h
+++ b/libopenfpga/libarchopenfpga/src/pb_type_annotation.h
@@ -47,8 +47,10 @@ class PbTypeAnnotation {
     std::string circuit_model_name() const;
     int physical_pb_type_index_factor() const;
     int physical_pb_type_index_offset() const;
-    BasicPort physical_pb_type_ports(const std::string& port_name) const;
-    int physical_pin_rotate_offsets(const std::string& port_name) const;
+    std::vector<std::string> port_names() const;
+    BasicPort physical_pb_type_port(const std::string& port_name) const;
+    int physical_pin_rotate_offset(const std::string& port_name) const;
+    std::vector<std::string> interconnect_names() const;
     std::string interconnect_circuit_model_name(const std::string& interc_name) const;
   public: /* Public mutators */
     void set_operating_pb_type_name(const std::string& name);
diff --git a/libopenfpga/libarchopenfpga/src/read_xml_pb_type_annotation.cpp b/libopenfpga/libarchopenfpga/src/read_xml_pb_type_annotation.cpp
index 25e1e12f8..253053bf5 100644
--- a/libopenfpga/libarchopenfpga/src/read_xml_pb_type_annotation.cpp
+++ b/libopenfpga/libarchopenfpga/src/read_xml_pb_type_annotation.cpp
@@ -75,7 +75,6 @@ void read_xml_pb_type_annotation(pugi::xml_node& xml_pb_type,
   /* Find the name of pb_type */
   const std::string& name_attr = get_attribute(xml_pb_type, "name", loc_data).as_string();
   const std::string& physical_name_attr = get_attribute(xml_pb_type, "physical_pb_type_name", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string();
-  const std::string& physical_mode_name_attr = get_attribute(xml_pb_type, "physical_mode_name", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string();
 
   /* If both names are not empty, this is a operating pb_type */
   if ( (false == name_attr.empty()) 
@@ -122,9 +121,11 @@ void read_xml_pb_type_annotation(pugi::xml_node& xml_pb_type,
   /* Parse mode bits which are applied to both pb_types */
   pb_type_annotation.set_mode_bits(get_attribute(xml_pb_type, "mode_bits", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string());
 
-  /* If this is a physical pb_type, circuit model name is a mandatory attribute */
+  /* If this is a physical pb_type, circuit model name is an optional attribute, 
+   * which is applicable to leaf pb_type in the hierarchy 
+   */
   if (true == pb_type_annotation.is_physical_pb_type()) {
-    pb_type_annotation.set_circuit_model_name(get_attribute(xml_pb_type, "circuit_model_name", loc_data).as_string());
+    pb_type_annotation.set_circuit_model_name(get_attribute(xml_pb_type, "circuit_model_name", loc_data, pugiutil::ReqOpt::OPTIONAL).as_string());
   }
 
   /* If this is an operating pb_type, index factor and offset may be optional needed */
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_openfpga_arch.cpp b/libopenfpga/libarchopenfpga/src/write_xml_openfpga_arch.cpp
index e262735e4..b71853156 100644
--- a/libopenfpga/libarchopenfpga/src/write_xml_openfpga_arch.cpp
+++ b/libopenfpga/libarchopenfpga/src/write_xml_openfpga_arch.cpp
@@ -16,6 +16,7 @@
 #include "write_xml_simulation_setting.h"
 #include "write_xml_config_protocol.h"
 #include "write_xml_routing_circuit.h"
+#include "write_xml_pb_type_annotation.h"
 #include "write_xml_openfpga_arch.h"
 
 /********************************************************************
@@ -57,6 +58,10 @@ void write_xml_openfpga_arch(const char* fname,
   /* Write the direct connection circuit definition */
   write_xml_direct_circuit(fp, fname, openfpga_arch.circuit_lib, openfpga_arch.direct2circuit);
 
+
+  /* Write the pb_type annotations */
+  openfpga::write_xml_pb_type_annotations(fp, fname, openfpga_arch. pb_type_annotations);
+
   fp << "</openfpga_architecture>" << "\n";
 
   /* Write the simulation */
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.cpp b/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.cpp
new file mode 100644
index 000000000..a771c782d
--- /dev/null
+++ b/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.cpp
@@ -0,0 +1,224 @@
+/********************************************************************
+ * This file includes functions that outputs pb_type annotations to XML format
+ *******************************************************************/
+/* Headers from system goes first */
+#include <string>
+#include <algorithm>
+
+/* Headers from vtr util library */
+#include "vtr_assert.h"
+#include "vtr_log.h"
+#include "openfpga_digest.h"
+
+/* Headers from readarchopenfpga library */
+#include "write_xml_utils.h" 
+#include "write_xml_pb_type_annotation.h"
+
+/* namespace openfpga begins */
+namespace openfpga {
+
+/********************************************************************
+ * Generate the full hierarchy name for a operating pb_type
+ *******************************************************************/
+static 
+std::string generate_operating_pb_type_hierarchy_name(const PbTypeAnnotation& pb_type_annotation) {
+  /* Iterate over the parent_pb_type and modes names, they should well match */
+  VTR_ASSERT_SAFE(pb_type_annotation.operating_parent_pb_type_names().size() == pb_type_annotation.operating_parent_mode_names().size());
+
+  std::string hie_name;
+
+  for (size_t i = 0 ; i < pb_type_annotation.operating_parent_pb_type_names().size(); ++i) {
+    hie_name += pb_type_annotation.operating_parent_pb_type_names()[i];
+    hie_name += std::string("[");
+    hie_name += pb_type_annotation.operating_parent_mode_names()[i];
+    hie_name += std::string("]");
+    hie_name += std::string(".");
+  }
+
+  /* Add the leaf pb_type */
+  hie_name += pb_type_annotation.operating_pb_type_name();
+
+  return hie_name;
+}
+
+/********************************************************************
+ * Generate the full hierarchy name for a operating pb_type
+ *******************************************************************/
+static 
+std::string generate_physical_pb_type_hierarchy_name(const PbTypeAnnotation& pb_type_annotation) {
+  /* Iterate over the parent_pb_type and modes names, they should well match */
+  VTR_ASSERT_SAFE(pb_type_annotation.physical_parent_pb_type_names().size() == pb_type_annotation.physical_parent_mode_names().size());
+
+  std::string hie_name;
+
+  for (size_t i = 0 ; i < pb_type_annotation.physical_parent_pb_type_names().size(); ++i) {
+    hie_name += pb_type_annotation.physical_parent_pb_type_names()[i];
+    hie_name += std::string("[");
+    hie_name += pb_type_annotation.physical_parent_mode_names()[i];
+    hie_name += std::string("]");
+    hie_name += std::string(".");
+  }
+
+  /* Add the leaf pb_type */
+  hie_name += pb_type_annotation.physical_pb_type_name();
+
+  return hie_name;
+}
+
+/********************************************************************
+ * Generate the full hierarchy name for a operating pb_type
+ *******************************************************************/
+static 
+std::string generate_physical_pb_port_name(const BasicPort& pb_port) {
+  std::string port_name;
+
+  /* Output format: <port_name>[<LSB>:<MSB>] */
+  port_name += pb_port.get_name();
+  port_name += std::string("[");
+  port_name += std::to_string(pb_port.get_lsb());
+  port_name += std::string(":");
+  port_name += std::to_string(pb_port.get_msb());
+  port_name += std::string("]");
+
+  return port_name;
+}
+
+/********************************************************************
+ * A writer to output an pb_type interconnection annotation to XML format
+ *******************************************************************/
+static 
+void write_xml_interconnect_annotation(std::fstream& fp,
+                                       const char* fname,
+                                       const openfpga::PbTypeAnnotation& pb_type_annotation,
+                                       const std::string& interc_name) {
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+
+  fp << "\t\t\t" << "<interconnect";
+ 
+  write_xml_attribute(fp, "name", interc_name.c_str());
+  write_xml_attribute(fp, "circuit_model_name", pb_type_annotation.interconnect_circuit_model_name(interc_name).c_str());
+
+  fp << "/>" << "\n";
+}
+
+/********************************************************************
+ * A writer to output an pb_type port annotation to XML format
+ *******************************************************************/
+static 
+void write_xml_pb_port_annotation(std::fstream& fp,
+                                  const char* fname,
+                                  const openfpga::PbTypeAnnotation& pb_type_annotation,
+                                  const std::string& port_name) {
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+
+  fp << "\t\t\t" << "<port";
+ 
+  write_xml_attribute(fp, "name", port_name.c_str());
+  write_xml_attribute(fp, "physical_mode_port", generate_physical_pb_port_name(pb_type_annotation.physical_pb_type_port(port_name)).c_str());
+  write_xml_attribute(fp, "physical_mode_pin_rotate_offset", pb_type_annotation.physical_pin_rotate_offset(port_name));
+
+  fp << "/>" << "\n";
+}
+
+/********************************************************************
+ * A writer to output a device variation in a technology library to XML format
+ *******************************************************************/
+static 
+void write_xml_pb_type_annotation(std::fstream& fp,
+                                  const char* fname,
+                                  const openfpga::PbTypeAnnotation& pb_type_annotation) {
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+
+  fp << "\t\t" << "<pb_type";
+
+  /* Write up name of the pb_type, which is different by the type of pb_type
+   * 1. operating pb_type, we output name, physical_pb_type_name
+   * 1. physical pb_type, we output name
+   */
+  if (true == pb_type_annotation.is_operating_pb_type()) { 
+    write_xml_attribute(fp, "name", generate_operating_pb_type_hierarchy_name(pb_type_annotation).c_str());
+    write_xml_attribute(fp, "physical_pb_type_name", generate_physical_pb_type_hierarchy_name(pb_type_annotation).c_str());
+  }
+  
+  if (true == pb_type_annotation.is_physical_pb_type()) { 
+    write_xml_attribute(fp, "name", generate_physical_pb_type_hierarchy_name(pb_type_annotation).c_str());
+  }
+
+  /* Output physical mode name */
+  if (!pb_type_annotation.physical_mode_name().empty()) { 
+    write_xml_attribute(fp, "physical_mode_name", pb_type_annotation.physical_mode_name().c_str());
+  }
+
+  /* Output idle mode name */
+  if (!pb_type_annotation.idle_mode_name().empty()) { 
+    write_xml_attribute(fp, "idle_mode_name", pb_type_annotation.idle_mode_name().c_str());
+  }
+
+  /* Output mode_bits */
+  if (!pb_type_annotation.mode_bits().empty()) { 
+    write_xml_attribute(fp, "mode_bits", pb_type_annotation.mode_bits().c_str());
+  }
+
+  /* Output circuit model name */
+  if (!pb_type_annotation.circuit_model_name().empty()) { 
+    write_xml_attribute(fp, "circuit_model_name", pb_type_annotation.circuit_model_name().c_str());
+  }
+
+  /* Output physical mode index factor and offset, only applicable to operating mode */
+  if (true == pb_type_annotation.is_operating_pb_type()) { 
+    write_xml_attribute(fp, "physical_pb_type_index_factor", pb_type_annotation.physical_pb_type_index_factor());
+    write_xml_attribute(fp, "physical_pb_type_index_offset", pb_type_annotation.physical_pb_type_index_offset());
+  }
+
+  /* If there are interconnect definition or port definition, output them
+   * Otherwise we can finish here 
+   */
+  if ( (0 == pb_type_annotation.interconnect_names().size())
+    && (0 == pb_type_annotation.port_names().size()) ) {
+    fp << "/>" << "\n";
+    return;
+  }
+
+  fp << ">" << "\n";
+
+  /* Output interconnects if there are any */
+  for (const std::string& interc_name : pb_type_annotation.interconnect_names()) {
+    write_xml_interconnect_annotation(fp, fname, pb_type_annotation, interc_name);
+  }
+
+  /* Output pb_type ports if there are any */
+  for (const std::string& port_name : pb_type_annotation.port_names()) {
+    write_xml_pb_port_annotation(fp, fname, pb_type_annotation, port_name);
+  }
+ 
+  fp << "\t\t</pb_type>" << "\n";
+}
+
+/********************************************************************
+ * A writer to output a number of pb_type annotations to XML format
+ *******************************************************************/
+void write_xml_pb_type_annotations(std::fstream& fp,
+                                   const char* fname,
+                                   const std::vector<PbTypeAnnotation>& pb_type_annotations) {
+  /* Validate the file stream */
+  openfpga::check_file_stream(fname, fp);
+  
+  /* Write the root node for pb_type annotations, 
+   * we apply a tab becuase pb_type annotations is just a subnode 
+   * under the root node <openfpga_arch>
+   */
+  fp << "\t" << "<pb_type_annotations>" << "\n";
+
+  /* Write device model one by one */ 
+  for (const PbTypeAnnotation& pb_type_annotation : pb_type_annotations) {
+    write_xml_pb_type_annotation(fp, fname, pb_type_annotation);
+  }
+
+  /* Write the root node for pb_type annotations */
+  fp << "\t" << "</pb_type_annotations>" << "\n";
+}
+
+} /* namespace openfpga ends */
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.h b/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.h
new file mode 100644
index 000000000..e40b5ad4e
--- /dev/null
+++ b/libopenfpga/libarchopenfpga/src/write_xml_pb_type_annotation.h
@@ -0,0 +1,22 @@
+#ifndef WRITE_XML_PB_TYPE_ANNOTATION_H
+#define WRITE_XML_PB_TYPE_ANNOTATION_H
+
+/********************************************************************
+ * Include header files that are required by function declaration
+ *******************************************************************/
+#include <fstream>
+#include "pb_type_annotation.h"
+
+/********************************************************************
+ * Function declaration
+ *******************************************************************/
+/* namespace openfpga begins */
+namespace openfpga {
+
+void write_xml_pb_type_annotations(std::fstream& fp,
+                                   const char* fname,
+                                   const std::vector<PbTypeAnnotation>& pb_type_annotations);
+
+} /* namespace openfpga ends */
+
+#endif
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_utils.cpp b/libopenfpga/libarchopenfpga/src/write_xml_utils.cpp
index ad887e10c..e4d32e720 100644
--- a/libopenfpga/libarchopenfpga/src/write_xml_utils.cpp
+++ b/libopenfpga/libarchopenfpga/src/write_xml_utils.cpp
@@ -46,6 +46,21 @@ void write_xml_attribute(std::fstream& fp,
   fp << "\""; 
 }
 
+/********************************************************************
+ * A most utilized function to write an XML attribute to file
+ * This accepts the value as a float
+ *******************************************************************/
+void write_xml_attribute(std::fstream& fp, 
+                         const char* attr,
+                         const int& value) {
+  /* Validate the file stream */
+  openfpga::valid_file_stream(fp);
+
+  fp << " " << attr << "=\"";
+  fp << value;
+  fp << "\""; 
+}
+
 /********************************************************************
  * A most utilized function to write an XML attribute to file
  * This accepts the value as a float
diff --git a/libopenfpga/libarchopenfpga/src/write_xml_utils.h b/libopenfpga/libarchopenfpga/src/write_xml_utils.h
index a827727e4..3976d78b9 100644
--- a/libopenfpga/libarchopenfpga/src/write_xml_utils.h
+++ b/libopenfpga/libarchopenfpga/src/write_xml_utils.h
@@ -18,6 +18,10 @@ void write_xml_attribute(std::fstream& fp,
                          const char* attr,
                          const bool& value);
 
+void write_xml_attribute(std::fstream& fp, 
+                         const char* attr,
+                         const int& value);
+
 void write_xml_attribute(std::fstream& fp, 
                          const char* attr,
                          const float& value);
diff --git a/libopenfpga/libopenfpgautil/src/openfpga_pb_parser.cpp b/libopenfpga/libopenfpgautil/src/openfpga_pb_parser.cpp
index ee674b928..3c174f589 100644
--- a/libopenfpga/libopenfpgautil/src/openfpga_pb_parser.cpp
+++ b/libopenfpga/libopenfpgautil/src/openfpga_pb_parser.cpp
@@ -67,6 +67,7 @@ void PbParser::parse() {
   /* The last pb is the leaf node.
    * It should NOT be empty and should NOT contain any brackets!  
    */
+  VTR_ASSERT(0 < pb_tokens.size());
   VTR_ASSERT(false == pb_tokens.back().empty());
   VTR_ASSERT(pb_tokens.back().find(bracket_.x()) == std::string::npos);
   VTR_ASSERT(pb_tokens.back().find(bracket_.y()) == std::string::npos);
diff --git a/libopenfpga/libopenfpgautil/src/openfpga_port_parser.cpp b/libopenfpga/libopenfpgautil/src/openfpga_port_parser.cpp
index 78f357b82..2006275dc 100644
--- a/libopenfpga/libopenfpgautil/src/openfpga_port_parser.cpp
+++ b/libopenfpga/libopenfpgautil/src/openfpga_port_parser.cpp
@@ -64,7 +64,7 @@ void PortParser::parse() {
 
   /* If we only have one token */
   if (1 == port_tokens.size()) {
-    port_.set_width(0); 
+    port_.set_width(1); 
     return; /* We can finish here */
   }
 
@@ -75,21 +75,22 @@ void PortParser::parse() {
   VTR_ASSERT_SAFE (1 == port_tokens.size());
 
   /* Split the pin string now */
-  tokenizer.set_data(port_tokens[0]);
+  tokenizer.set_data(pin_tokens[0]);
   pin_tokens = tokenizer.split(delim_);
 
   /* Check if we have LSB and MSB or just one */
   if ( 1 == pin_tokens.size() ) {
     /* Single pin */
-    port_.set_width(stoi(pin_tokens[0]), stoi(pin_tokens[0])); 
+    port_.set_width(std::stoi(pin_tokens[0]), std::stoi(pin_tokens[0])); 
   } else if ( 2 == pin_tokens.size() ) {
-    /* A number of pin */
-    port_.set_width(stoi(pin_tokens[0]), stoi(pin_tokens[1])); 
-  }
-
-  /* Re-order to ensure LSB <= MSB */
-  if (false == port_.is_valid()) {
-    port_.revert(); 
+    /* A number of pins. 
+     * Note that we always use the LSB for token[0] and MSB for token[1] 
+     */
+    if (std::stoi(pin_tokens[1]) < std::stoi(pin_tokens[0])) {
+      port_.set_width(std::stoi(pin_tokens[1]), std::stoi(pin_tokens[0])); 
+    } else {
+      port_.set_width(std::stoi(pin_tokens[0]), std::stoi(pin_tokens[1])); 
+    }
   }
 
   return;