diff --git a/docs/source/manual/file_formats/index.rst b/docs/source/manual/file_formats/index.rst
index 45c91d0ce..1749fc68d 100644
--- a/docs/source/manual/file_formats/index.rst
+++ b/docs/source/manual/file_formats/index.rst
@@ -35,3 +35,5 @@ OpenFPGA widely uses XML format for interchangable files
    pin_table_file
 
    clock_network
+
+   io_naming_file
diff --git a/docs/source/manual/file_formats/io_naming_file.rst b/docs/source/manual/file_formats/io_naming_file.rst
new file mode 100644
index 000000000..d733be45a
--- /dev/null
+++ b/docs/source/manual/file_formats/io_naming_file.rst
@@ -0,0 +1,65 @@
+.. _file_formats_io_naming_file:
+
+Fabric I/O Naming (.xml)
+------------------------
+
+The XML-based description language is used to describe
+
+- I/O names for an FPGA fabric when creating a top-level wrapper
+- I/O connections between the fabric and top-level wrappers
+
+Using the description language, users can customize the I/O names for each pin/port of an FPGA fabric, including dummy pins (not from an FPGA fabric but required for system integration).
+
+Under the root node ``<ports>``, naming rules can be defined line-by-line through syntax ``<port>``.
+
+.. code-block:: xml
+
+  <ports> 
+    <port top_name="<string>" core_name="<string>" is_dummy="<bool>" direction="<string>"> 
+  </ports> 
+
+Please be aware of the following restrictions:
+
+.. note:: Please note that when naming rules should be applied to a port at its full size. For example, given a port of ``in[0:31]``, naming rules should cover all the 32 bits.
+
+.. note:: Please note that we currently only supports port splitting at the top-level wrapper. For example, there is a port ``a[0:9]`` from the FPGA fabric, it can be split to ``a0[0:4]`` and ``a1[0:4]`` at the top-level wrapper.
+
+.. warning:: Port grouping is **NOT** supported yet. For example, there are ports ``b[0:7]`` and ``c[0:7]`` from the FPGA fabric, it can **NOT** be grouped to a port ``bnc[0:15]`` at the top-level wrapper.
+
+Detailed syntax are presented as follows.
+
+.. option:: top_name="<string>"
+
+  Define the port name and width which will appear in the top-level wrapper. For example, 
+
+  .. code-block:: xml
+
+   top_name="a[0:2]"
+
+.. option:: core_name="<string>"
+
+  Define the port name and width which exists in the current FPGA fabric. For example, 
+
+  .. note:: You can find the available ports in the current top-level module of FPGA netlists. See details in :ref:`fabric_netlists`. 
+
+  .. code-block:: xml
+
+    core_name="gfpga_pad_GPIO_PAD[0:2]"
+
+.. option:: is_dummy="<bool>"
+
+  Define if the port is a dummy one in the top-level wrapper, which does not connect to any pin/port of the current FPGA fabric. For example, 
+
+  .. note:: When a dummy port is defined. ``core_name`` is not required.
+
+  .. code-block:: xml
+
+   is_dummy="true"
+
+.. option:: direction="<string>"
+
+  Direction can be ``input``|``output``|``inout``. Only applicable to dummy ports. For example, 
+
+  .. code-block:: xml
+
+   direction="input"
diff --git a/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst b/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
index 68fd3d251..7f891eecd 100644
--- a/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
+++ b/docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst
@@ -290,7 +290,7 @@ add_fpga_core_to_fabric
 
   .. option:: --io_naming <string>
 
-    This is optional. Specify the I/O naming rules when connecting I/Os of ``fpga_core`` module to the top-level module ``fpga_top``. If not defined, the ``fpga_top`` will be the same as ``fpga_core`` w.r.t. ports. See details about the file format of I/O naming rules in :ref:`file_format_io_naming_file`.
+    This is optional. Specify the I/O naming rules when connecting I/Os of ``fpga_core`` module to the top-level module ``fpga_top``. If not defined, the ``fpga_top`` will be the same as ``fpga_core`` w.r.t. ports. See details about the file format of I/O naming rules in :ref:`file_formats_io_naming_file`.
 
   .. option:: --instance_name <string>