diff --git a/lib/earmark/options.ex b/lib/earmark/options.ex
index 0b3e1769..fd157f6f 100644
--- a/lib/earmark/options.ex
+++ b/lib/earmark/options.ex
@@ -17,6 +17,35 @@ defmodule Earmark.Options do
   All other options are passed onto Earmark.Parser.as_ast/`2`
   """
 
+  @type t :: %__MODULE__{
+          annotations: String.t() | nil,
+          breaks: boolean(),
+          code_class_prefix: String.t() | nil,
+          compact_output: boolean(),
+          eex: boolean(),
+          escape: boolean(),
+          file: String.t() | nil,
+          footnote_offset: non_neg_integer(),
+          footnotes: boolean(),
+          gfm: boolean(),
+          gfm_tables: boolean(),
+          ignore_strings: boolean(),
+          inner_html: boolean(),
+          line: non_neg_integer(),
+          mapper: (list(any()), function() -> {:ok, list(any())} | {:error, any()}),
+          mapper_with_timeout:
+            (list(any()), function(), integer() -> {:ok, list(any())} | {:error, any()}),
+          messages: list(Earmark.Error.t()) | [],
+          pedantic: boolean(),
+          postprocessor: function() | nil,
+          pure_links: boolean(),
+          sub_sup: boolean(),
+          registered_processors: list(any()),
+          smartypants: boolean(),
+          template: boolean(),
+          timeout: integer() | nil,
+          wikilinks: boolean()
+        }
   defstruct annotations: nil,
             breaks: false,
             code_class_prefix: nil,
diff --git a/lib/earmark/tag_specific_processors.ex b/lib/earmark/tag_specific_processors.ex
index edf35442..24979a34 100644
--- a/lib/earmark/tag_specific_processors.ex
+++ b/lib/earmark/tag_specific_processors.ex
@@ -1,5 +1,4 @@
 defmodule Earmark.TagSpecificProcessors do
-
   @moduledoc """
   This struct represents a list of tuples `{tag, function}` from which a postprocessing function
   can be constructed
@@ -21,7 +20,7 @@ defmodule Earmark.TagSpecificProcessors do
       ...(2)> make_postprocessor(tsp).({"x", [], nil, nil})
       {"x", [], nil, nil}
   """
-
+  @type t :: %__MODULE__{tag_functions: list()}
   defstruct tag_functions: []
 
   @doc """
@@ -29,8 +28,10 @@ defmodule Earmark.TagSpecificProcessors do
   to the tag of the node, and apply the node to it if such a function was found.
   """
   def make_postprocessor(%__MODULE__{tag_functions: tfs}) do
-    fn {_, _, _, _}=node -> _postprocess(node, tfs)
-       other             -> other end
+    fn
+      {_, _, _, _} = node -> _postprocess(node, tfs)
+      other -> other
+    end
   end
 
   @doc """
@@ -41,22 +42,25 @@ defmodule Earmark.TagSpecificProcessors do
 
   """
   def new, do: %__MODULE__{}
-  def new({_, _}=tf), do: %__MODULE__{tag_functions: [tf]}
+  def new({_, _} = tf), do: %__MODULE__{tag_functions: [tf]}
   def new(tfs), do: %__MODULE__{tag_functions: tfs}
 
-
   @doc """
   Prepends a tuple {tag, function} to the list of such tuples.
   """
   def prepend_tag_function(tsp, tag, function), do: prepend_tag_function(tsp, {tag, function})
-  def prepend_tag_function(%__MODULE__{tag_functions: tfs}=tsp, tf) do
-    %{tsp | tag_functions: [tf|tfs]}
+
+  def prepend_tag_function(%__MODULE__{tag_functions: tfs} = tsp, tf) do
+    %{tsp | tag_functions: [tf | tfs]}
   end
 
-  defp _postprocess({t, _, _, _}=node, tfs) do
-    fun = tfs
-    |> Enum.find_value(fn {t_, f} -> if t == t_, do: f end)
+  defp _postprocess({t, _, _, _} = node, tfs) do
+    fun =
+      tfs
+      |> Enum.find_value(fn {t_, f} -> if t == t_, do: f end)
+
     if fun, do: fun.(node), else: node
   end
 end
+
 #  SPDX-License-Identifier: Apache-2.0
diff --git a/lib/earmark_parser/line.ex b/lib/earmark_parser/line.ex
index 5ff85540..eb643daf 100644
--- a/lib/earmark_parser/line.ex
+++ b/lib/earmark_parser/line.ex
@@ -1,67 +1,215 @@
 defmodule Earmark.Parser.Line do
-
   @moduledoc false
+  alias Earmark.Parser.Line
+
+  @type annotation :: any() | nil
+  @type lnb :: integer()
+  @type line :: String.t()
+  @type indent :: integer()
+  @type content :: String.t()
+  @type ial :: any() | nil
+  @type type :: String.t()
+  @type level :: integer()
+  @type delimiter :: String.t()
+  @type language :: any()
+  @type tag :: String.t()
+  @type complete :: boolean()
+  @type id :: any()
+  @type url :: String.t() | URI.t()
+  @type title :: String.t()
+  @type bullet :: String.t()
+  @type initial_indent :: integer()
+  @type list_indent :: integer()
 
-defmodule Blank  do
+  defmodule Blank do
     @moduledoc false
+
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, content: "")
   end
-defmodule Ruler  do
+
+  defmodule Ruler do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            type: Line.type()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, type: "- or * or _")
   end
 
-defmodule Heading  do
+  defmodule Heading do
     @moduledoc false
-    defstruct(annotation: nil, ial: nil, lnb: 0, line: "", indent: -1, level: 1, content: "inline text")
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            ial: Line.ial(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            level: Line.level(),
+            content: Line.content()
+          }
+
+    defstruct(
+      annotation: nil,
+      ial: nil,
+      lnb: 0,
+      line: "",
+      indent: -1,
+      level: 1,
+      content: "inline text"
+    )
   end
 
-defmodule BlockQuote  do
+  defmodule BlockQuote do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            ial: Line.ial(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            content: Line.content()
+          }
     defstruct(annotation: nil, ial: nil, lnb: 0, line: "", indent: -1, content: "text")
   end
 
-defmodule Indent  do
+  defmodule Indent do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            level: Line.level(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, level: 0, content: "text")
   end
 
-defmodule Fence  do
+  defmodule Fence do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            delimiter: Line.delimiter(),
+            language: Line.language()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, delimiter: "~ or `", language: nil)
   end
 
-defmodule HtmlOpenTag  do
+  defmodule HtmlOpenTag do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            tag: Line.tag(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, tag: "", content: "")
   end
 
-defmodule HtmlCloseTag  do
+  defmodule HtmlCloseTag do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            tag: Line.tag()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, tag: "<... to eol")
   end
-defmodule HtmlComment  do
+
+  defmodule HtmlComment do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            complete: Line.complete()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, complete: true)
   end
 
-defmodule HtmlOneLine  do
+  defmodule HtmlOneLine do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            tag: Line.tag(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, tag: "", content: "")
   end
 
-defmodule IdDef  do
+  defmodule IdDef do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            id: Line.id(),
+            url: Line.url(),
+            title: Line.title()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, id: nil, url: nil, title: nil)
   end
 
-defmodule FnDef  do
+  defmodule FnDef do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            id: Line.id(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, id: nil, content: "text")
   end
 
-defmodule ListItem do
+  defmodule ListItem do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            ial: Line.ial(),
+            lnb: Line.lnb(),
+            type: Line.type(),
+            line: Line.line(),
+            indent: Line.indent(),
+            bullet: Line.bullet(),
+            content: Line.content(),
+            initial_indent: Line.initial_indent(),
+            list_indent: Line.list_indent()
+          }
+
     defstruct(
       annotation: nil,
       ial: nil,
@@ -76,23 +224,71 @@ defmodule ListItem do
     )
   end
 
-defmodule SetextUnderlineHeading  do
+  defmodule SetextUnderlineHeading do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            level: Line.level()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, level: 1)
   end
 
-defmodule TableLine  do
+  defmodule TableLine do
     @moduledoc false
-    defstruct(annotation: nil, lnb: 0, line: "", indent: -1, content: "", columns: 0, is_header: false, needs_header: false)
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            content: Line.content(),
+            columns: integer(),
+            is_header: boolean(),
+            needs_header: boolean()
+          }
+
+    defstruct(
+      annotation: nil,
+      lnb: 0,
+      line: "",
+      indent: -1,
+      content: "",
+      columns: 0,
+      is_header: false,
+      needs_header: false
+    )
   end
 
-defmodule Ial  do
+  defmodule Ial do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            ial: Line.ial(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            attrs: String.t(),
+            verbatim: String.t()
+          }
+
     defstruct(annotation: nil, ial: nil, lnb: 0, line: "", indent: -1, attrs: "", verbatim: "")
   end
-defmodule Text  do
+
+  defmodule Text do
     @moduledoc false
+    @type t :: %__MODULE__{
+            annotation: Line.annotation(),
+            lnb: Line.lnb(),
+            line: Line.line(),
+            indent: Line.indent(),
+            content: Line.content()
+          }
+
     defstruct(annotation: nil, lnb: 0, line: "", indent: -1, content: "")
   end
 end
+
 # SPDX-License-Identifier: Apache-2.0