diff --git a/lib/openflow/actions/copy_ttl_in.ex b/lib/openflow/actions/copy_ttl_in.ex
index 83347b4..6b4fd2c 100644
--- a/lib/openflow/actions/copy_ttl_in.ex
+++ b/lib/openflow/actions/copy_ttl_in.ex
@@ -1,18 +1,37 @@
 defmodule Openflow.Action.CopyTtlIn do
+  @moduledoc """
+  Copy the TTL from next-to-outermost to outermost header with TTL.\\
+  Copy can be IP-to-IP, MPLS-to-MPLS, or IP-to-MPLS.
+  """
+
   defstruct([])
 
   alias __MODULE__
 
+  @type t :: %CopyTtlIn{}
+
+  @spec ofpat() :: 12
   def ofpat, do: 12
 
+  @doc """
+  Create a copy_ttl_in action struct
+
+  ## Example:
+  ```elixir
+  iex> %CopyTtlIn{} = Openflow.Action.CopyTtlIn.new()
+  ```
+  """
+  @spec new() :: CopyTtlIn.t()
   def new do
     %CopyTtlIn{}
   end
 
+  @spec to_binary(CopyTtlIn.t()) :: <<_::16, _::_*8>>
   def to_binary(%CopyTtlIn{}) do
     <<12::16, 8::16, 0::size(4)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: CopyTtlIn.t()
   def read(<<12::16, 8::16, _::size(4)-unit(8)>>) do
     %CopyTtlIn{}
   end
diff --git a/lib/openflow/actions/copy_ttl_out.ex b/lib/openflow/actions/copy_ttl_out.ex
index 759c0ad..7ce6dcf 100644
--- a/lib/openflow/actions/copy_ttl_out.ex
+++ b/lib/openflow/actions/copy_ttl_out.ex
@@ -1,18 +1,38 @@
 defmodule Openflow.Action.CopyTtlOut do
+  @moduledoc """
+  Copy the TTL from outermost to next-to-outermost header with TTL.\\
+  Copy can be IP-to-IP, MPLS-to-MPLS, or MPLS-to-IP.
+  """
+
   defstruct([])
 
   alias __MODULE__
 
+  @type t :: %CopyTtlOut{}
+
+  @spec ofpat() :: 11
   def ofpat, do: 11
 
+  @doc """
+  Create a copy_ttl_out action structure
+
+  ## Example
+
+  ```elixir
+  iex> %CopyTtlOut{} = Openflow.Action.CopyTtlOut.new()
+  ```
+  """
+  @spec new() :: CopyTtlOut.t()
   def new do
     %CopyTtlOut{}
   end
 
+  @spec to_binary(CopyTtlIn.t()) :: <<_::16, _::_*8>>
   def to_binary(%CopyTtlOut{}) do
     <<11::16, 8::16, 0::size(4)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: CopyTtlOut.t()
   def read(<<11::16, 8::16, _::size(4)-unit(8)>>) do
     %CopyTtlOut{}
   end
diff --git a/lib/openflow/actions/dec_mpls_ttl.ex b/lib/openflow/actions/dec_mpls_ttl.ex
index 2931954..d3309cd 100644
--- a/lib/openflow/actions/dec_mpls_ttl.ex
+++ b/lib/openflow/actions/dec_mpls_ttl.ex
@@ -1,18 +1,39 @@
 defmodule Openflow.Action.DecMplsTtl do
+  @moduledoc """
+  Decrement MPLS TTL action
+  """
+
   defstruct([])
 
   alias __MODULE__
 
+  @type t :: %DecMplsTtl{}
+
+  @spec ofpat() :: 16
   def ofpat, do: 16
 
+  @doc """
+  Create a new dec_mpls_ttl action struct.
+
+  Note: Need to be specified the one of `ETH_P_MPLS_*` on `eth_type` match field when using this action.
+
+  ## Example:
+
+  ````elixir
+  iex> %DecMplsTtl{} = DecMplsTtl.new()
+  ````
+  """
+  @spec new() :: t()
   def new do
     %DecMplsTtl{}
   end
 
+  @spec to_binary(t()) :: <<_::16, _::_*8>>
   def to_binary(%DecMplsTtl{}) do
     <<16::16, 8::16, 0::size(4)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: t()
   def read(<<16::16, 8::16, _::size(4)-unit(8)>>) do
     %DecMplsTtl{}
   end
diff --git a/lib/openflow/actions/dec_nw_ttl.ex b/lib/openflow/actions/dec_nw_ttl.ex
index 6d23b5d..30c6b0d 100644
--- a/lib/openflow/actions/dec_nw_ttl.ex
+++ b/lib/openflow/actions/dec_nw_ttl.ex
@@ -1,4 +1,7 @@
 defmodule Openflow.Action.DecNwTtl do
+  @moduledoc """
+  """
+
   defstruct([])
 
   alias __MODULE__
diff --git a/lib/openflow/actions/output.ex b/lib/openflow/actions/output.ex
index 96e52c5..e0c0bfd 100644
--- a/lib/openflow/actions/output.ex
+++ b/lib/openflow/actions/output.ex
@@ -1,31 +1,67 @@
 defmodule Openflow.Action.Output do
-  defstruct(
-    port_number: 0,
-    max_len: :no_buffer
-  )
+  @moduledoc """
+  Action for sends packets out `port_number`.
+  """
+
+  defstruct port_number: 0,
+            max_len: :no_buffer
 
   alias __MODULE__
 
+  @type port_no ::
+          0..0xFFFFFFFF
+          | :max
+          | :in_port
+          | :table
+          | :normal
+          | :flood
+          | :all
+          | :controller
+          | :local
+          | :any
+
+  @type max_len :: 0..0xFFFFFFFF | :no_buffer | :max
+
+  @type t :: %Output{port_number: port_no(), max_len: max_len()}
+
+  @spec ofpat() :: 0
   def ofpat, do: 0
 
+  @doc """
+  Create a new output action structure
+
+  ## Options:
+    - `port_number`: port number that sends a packet from
+    - `max_len`: byte length of the packet that sends to the controller
+
+  ## Example
+
+  ```elixir
+  iex> %Output{port_number: 1, max_len: :no_buffer} = Output.new(1)
+  ```
+  """
+  @spec new([port_number: port_no, max_len: max_len()] | port_no()) :: Output.t()
   def new(options \\ [])
 
-  def new(port) when not is_list(port) do
-    new(port_number: port)
-  end
+  @spec new(port :: port_no()) :: Output.t()
+  def new(port) when is_atom(port) or is_integer(port),
+    do: new(port_number: port)
 
+  @spec new(options :: [port_number: port_no(), max_len: max_len()]) :: Output.t()
   def new(options) when is_list(options) do
     port_no = options[:port_number] || raise "port_number must be specified"
     max_len = options[:max_len] || :no_buffer
     %Output{port_number: port_no, max_len: max_len}
   end
 
+  @spec to_binary(Output.t()) :: <<_::16, _::_*8>>
   def to_binary(%Output{port_number: port_no, max_len: max_len}) do
     port_no_int = Openflow.Utils.get_enum(port_no, :openflow13_port_no)
     max_len = Openflow.Utils.get_enum(max_len, :controller_max_len)
     <<0::16, 16::16, port_no_int::32, max_len::16, 0::size(6)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: Output.t()
   def read(<<0::16, 16::16, port_no_int::32, max_len::16, _pad::size(6)-unit(8)>>) do
     port_no = Openflow.Utils.get_enum(port_no_int, :openflow13_port_no)
     max_len = Openflow.Utils.get_enum(max_len, :controller_max_len)
diff --git a/lib/openflow/actions/pop_mpls.ex b/lib/openflow/actions/pop_mpls.ex
index 91f6eaa..3d82f6e 100644
--- a/lib/openflow/actions/pop_mpls.ex
+++ b/lib/openflow/actions/pop_mpls.ex
@@ -1,12 +1,34 @@
 defmodule Openflow.Action.PopMpls do
+  @moduledoc """
+  Pop the out MPLS label
+
+  note: The one of ETH__P_MPLS_* is needed to be specified to eth_type field
+
+      send_flow_mod_add(
+        datapath_id,
+        match: Match.new(0x8847),
+        instructions: ApplyActions.new(PopMpls.new())
+      )
+  """
+
   defstruct(ethertype: 0x8847)
 
   alias __MODULE__
 
+  @type t :: %PopMpls{}
+
   @eth_p_mpls_uc 0x8847
 
+  @spec ofpat() :: 20
   def ofpat, do: 20
 
+  @doc """
+  Create a new pop_mpls action struct
+
+  0x8847(ETH_P_MPLS_UC) as default value.
+  """
+  @spec new() :: t()
+  @spec new(ethertype :: 0..0xFFFF) :: t()
   def new(ethertype \\ @eth_p_mpls_uc) do
     %PopMpls{ethertype: ethertype}
   end
diff --git a/lib/openflow/actions/pop_vlan.ex b/lib/openflow/actions/pop_vlan.ex
index 8ea4f26..5ad96c9 100644
--- a/lib/openflow/actions/pop_vlan.ex
+++ b/lib/openflow/actions/pop_vlan.ex
@@ -1,18 +1,38 @@
 defmodule Openflow.Action.PopVlan do
+  @moduledoc """
+  Pop the outer VLAN tag.
+
+  note: The one of ETH__P_802_* is needed to be specified to eth_type field
+      send_flow_mod_add(
+        datapath_id,
+        match: Match.new(eth_type: 0x8100),
+        instructions: ApplyActions.new(PopVlan.new())
+      )
+  """
+
   defstruct([])
 
   alias __MODULE__
 
+  @type t() :: %PopVlan{}
+
+  @spec ofpat() :: 18
   def ofpat, do: 18
 
+  @doc """
+  Create a new pop_vlan action struct
+  """
+  @spec new() :: t()
   def new do
     %PopVlan{}
   end
 
+  @spec to_binary(t()) :: <<_::16, _::_*8>>
   def to_binary(%PopVlan{}) do
     <<18::16, 8::16, 0::size(4)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: t()
   def read(<<18::16, 8::16, _::size(4)-unit(8)>>) do
     %PopVlan{}
   end
diff --git a/lib/openflow/actions/push_mpls.ex b/lib/openflow/actions/push_mpls.ex
index 9d55a28..caa2141 100644
--- a/lib/openflow/actions/push_mpls.ex
+++ b/lib/openflow/actions/push_mpls.ex
@@ -1,20 +1,43 @@
 defmodule Openflow.Action.PushMpls do
+  @moduledoc """
+  Push a new MPLS label
+
+      send_flow_mod_add(
+        datapath_id,
+        match: Match.new(),
+        instruction: ApplyActions.new(PushMpls.new())
+      )
+  """
+
   defstruct(ethertype: 0x8847)
 
   @eth_p_mpls_uc 0x8847
 
   alias __MODULE__
 
+  @type t :: %PushMpls{ethertype: 0..0xFFFF}
+
+  @spec ofpat() :: 19
   def ofpat, do: 19
 
+  @doc """
+  Create a new push_mpls action struct\\
+  0x8847(ETH_P_MPLS_UC) as a default value.
+
+      iex> %PushMpls{ethertype: 0x8847} = PushMpls.new()
+  """
+  @spec new() :: t()
+  @spec new(ethertype :: 0..0xFFFF) :: t()
   def new(ethertype \\ @eth_p_mpls_uc) do
     %PushMpls{ethertype: ethertype}
   end
 
+  @spec to_binary(t()) :: <<_::16, _::_*8>>
   def to_binary(%PushMpls{ethertype: ethertype}) do
     <<19::16, 8::16, ethertype::16, 0::size(2)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: t()
   def read(<<19::16, 8::16, ethertype::16, 0::size(2)-unit(8)>>) do
     %PushMpls{ethertype: ethertype}
   end
diff --git a/lib/openflow/actions/push_vlan.ex b/lib/openflow/actions/push_vlan.ex
index 8c8ca39..25221ac 100644
--- a/lib/openflow/actions/push_vlan.ex
+++ b/lib/openflow/actions/push_vlan.ex
@@ -1,18 +1,39 @@
 defmodule Openflow.Action.PushVlan do
+  @moduledoc """
+  Push a new VLAN tag
+
+      send_flow_mod_add(
+        datapath_id,
+        instructions: ApplyActions.new(PushVlan.new())
+      )
+  """
+
   defstruct(ethertype: 0x8100)
 
   alias __MODULE__
+  @type t :: %PushVlan{ethertype: 0..0xFFFF}
 
+  @spec ofpat() :: 17
   def ofpat, do: 17
 
+  @doc """
+  Create a new push_vlan action struct.\\
+  0x8100 is a default value.
+
+      iex> %PushVlan{ethertype: 0x8100} = PushVlan.new()
+  """
+  @spec new() :: t()
+  @spec new(ethertype :: 0..0xFFFF) :: t()
   def new(ethertype \\ 0x8100) do
     %PushVlan{ethertype: ethertype}
   end
 
+  @spec to_binary(t()) :: <<_::16, _::_*8>>
   def to_binary(%PushVlan{ethertype: ethertype}) do
     <<17::16, 8::16, ethertype::16, 0::size(2)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: t()
   def read(<<17::16, 8::16, ethertype::16, 0::size(2)-unit(8)>>) do
     %PushVlan{ethertype: ethertype}
   end
diff --git a/lib/openflow/actions/set_mpls_ttl.ex b/lib/openflow/actions/set_mpls_ttl.ex
index a82a0ec..84cfcfb 100644
--- a/lib/openflow/actions/set_mpls_ttl.ex
+++ b/lib/openflow/actions/set_mpls_ttl.ex
@@ -1,18 +1,38 @@
 defmodule Openflow.Action.SetMplsTtl do
+  @moduledoc """
+  Replace the existing MPLS TTL.\\
+  Only applies to the packets with an existing MPLS shim header.
+  """
+
   defstruct(ttl: 0)
 
   alias __MODULE__
 
+  @type t :: %SetMplsTtl{ttl: 0..0xFF}
+
+  @spec ofpat() :: 15
   def ofpat, do: 15
 
+  @doc """
+  Create a set_mpls_ttl action structure
+
+  ## Example:
+  ```elixir
+  iex> %SetMplsTtl{ttl: 64} = Openflow.Action.SetMplsTtl.new(64)
+  ```
+  """
+  @deprecated "OFPAT_SET_MPLS_TTL is deprecated in OpenFlow13, use SetField"
+  @spec new(0..0xFF) :: SetMplsTtl.t()
   def new(ttl) do
     %SetMplsTtl{ttl: ttl}
   end
 
+  @spec to_binary(SetMplsTtl.t()) :: <<_::16, _::_*8>>
   def to_binary(%SetMplsTtl{ttl: ttl}) do
     <<15::16, 8::16, ttl::8, 0::size(3)-unit(8)>>
   end
 
+  @spec read(<<_::16, _::_*8>>) :: SetMplsTtl.t()
   def read(<<15::16, 8::16, ttl::8, _::size(3)-unit(8)>>) do
     %SetMplsTtl{ttl: ttl}
   end
diff --git a/mix.exs b/mix.exs
index 1062030..c7d4380 100644
--- a/mix.exs
+++ b/mix.exs
@@ -36,13 +36,13 @@ defmodule Tres.Mixfile do
   defp docs do
     [
       groups_for_modules: groups_for_modules(),
-      formatters: ["html"],
+      formatters: ["html"]
     ]
   end
 
   defp groups_for_modules do
     [
-      "Actions": [
+      Actions: [
         Openflow.Action.Output,
         Openflow.Action.CopyTtlOut,
         Openflow.Action.CopyTtlIn,