diff --git a/libopenfpga/libarchopenfpga/src/pb_annotation.h b/libopenfpga/libarchopenfpga/src/pb_annotation.h
new file mode 100644
index 000000000..2cd92d3a7
--- /dev/null
+++ b/libopenfpga/libarchopenfpga/src/pb_annotation.h
@@ -0,0 +1,52 @@
+#ifndef PB_PHYSICAL_ANNOTATION_H
+#ifndef PB_PHYSICAL_ANNOTATION_H
+
+/********************************************************************
+ * Include header files required by the data structure definition
+ *******************************************************************/
+#include <vector>
+#include <map>
+
+/********************************************************************
+ * This file include the declaration of data structures
+ * to store physical pb_type annotation, including
+ * 1. the binding between operating pb_type and physical_pb_type
+ *    this also cover the binding between pins of any pair of pb_types
+ * 2. the binding between physical pb_type and circuit models
+ * 3. the binding between interconnect under pb_types and circuit models
+ *    This is only applicable to physical pb_types
+ *
+ * Each PhysicalPbAnnotation includes the binding for ONLY a pb_type
+ * defined in the architecture XML
+ *
+ * Note:
+ * 1. Keep this data structure as general as possible. It is supposed
+ *    to contain the raw data from architecture XML! If you want to link
+ *    to other data structures, please create another one in other header files
+ *******************************************************************/
+class PhysicalPbAnnotation {
+  private: /* Internal data */
+    /* Binding between physical pb_type and operating pb_type 
+     * both operating and physial pb_type names are the full names 
+     * defined in the hierarchy of pb_types
+     * e.g.
+     *    clb.fle[frac_logic].frac_lut6
+     */
+    std::string operating_pb_type_name_;
+    std::string physical_pb_type_name_;
+    std::string mode_bits_;
+    std::string circuit_model_name_;
+    int physical_pb_type_index_factor_;
+    int physical_pb_type_index_offset_;
+
+    /* Link from the pins under an operating pb_type to physical pb_type  */
+    std::vector<std::string> operating_pb_type_pin_names_;
+    std::vector<std::string> physical_pb_type_pin_names_;
+    std::vector<int> physical_pin_rotate_offset_;
+
+    /* Link between the interconnects under this pb_type and circuit model names */
+    std::vector<std:map<std::string, std::string>> interconnect_circuit_model_names_;
+};
+
+#endif
+