diff --git a/README.md b/README.md
index c88a4a9..01f7968 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ Create up-to-date [harpoon2] information to be used in a status-line
     - [Formatters](#formatters)
       - [The "short" builtin](#the-short-builtin)
       - [The "extended" builtin](#the-extended-builtin)
-      - [Modify a builtin](#modify-a-builtin)
+      - [Customize a builtin](#customize-a-builtin)
       - [Use a custom formatter](#use-a-custom-formatter)
   - [Harpoon lists](#harpoon-lists)
   - [Recipes](#recipes)
@@ -72,7 +72,7 @@ an empty string.
     "nvim-lualine/lualine.nvim",
     dependencies =  { "abeldekat/harpoonline", version = "*" },
     config = function()
-      local Harpoonline = require("harpoonline").setup() -- using default config
+      local Harpoonline = require("harpoonline").setup() -- using defaults
       local lualine_c = { Harpoonline.format, "filename" }
       require("lualine").setup({ sections = { lualine_c = lualine_c } })
     end,
@@ -134,16 +134,16 @@ Harpoonline.config = {
   ---@type string|nil
   icon = '󰀱',
 
-  -- Harpoon:list() retrieves the default list: The name of the list is nil.
-  -- The name to display can be configured by using default_list_name
+  -- Harpoon:list() retrieves the default list: The name of that list is nil.
+  -- default_list_name: Configures the display name for the default list.
   ---@type string
   default_list_name = '',
 
   ---@type string
-  formatter = 'extended', -- use a builtin formatter
+  formatter = 'extended', -- short -- use a builtin formatter
 
   ---@type fun():string|nil
-  custom_formatter = nil, -- use this formatter when supplied
+  custom_formatter = nil, -- use this formatter when configured
   ---@type fun()|nil
   on_update = nil, -- optional action to perform after update
 }
@@ -160,9 +160,12 @@ Scenario's:
 
 #### The "short" builtin
 
+Add to the config: `{ formatter = 'short'}`
+
 ```lua
-Harpoonline.config = {
-  formatter = 'short',
+---@class HarpoonlineBuiltinOptionsShort
+H.builtin_options_short = {
+  inner_separator = '|',
 }
 ```
 
@@ -172,46 +175,53 @@ Output B: :anchor:  `[2|3]`
 
 #### The "extended" builtin
 
-The default
-
-Output A: :anchor:  `1 2 3 -`
+This is the default formatter.
 
-Output B: :anchor:  `1 [2] 3 -`
+```lua
+---@class HarpoonlineBuiltinOptionsExtended
+H.builtin_options_extended = {
+  indicators = { '1', '2', '3', '4' },
+  active_indicators = { '[1]', '[2]', '[3]', '[4]' },
+  empty_slot = '·', -- interpunct, or middledot,
+  more_marks_indicator = '…', -- horizontal elipsis
+}
+```
 
-#### Modify a builtin
+Output A: :anchor:  `1 2 3 ·`
 
-Builtin formatters: `Harpoonline.formatters`
-The corresponding formatter specific options: `Harpoonline.formatter_opts`
+Output B: :anchor:  `1 [2] 3 ·`
 
-Modify "extended":
+#### Customize a builtin
 
 ```lua
 local Harpoonline = require("harpoonline")
+---@type HarpoonlineBuiltinOptionsExtended
+local opts = {
+  indicators = { "j", "k", "l", "h" },
+  active_indicators = { "<j>", "<k>", "<l>", "<h>" },
+}
 Harpoonline.setup({
-  custom_formatter = Harpoonline.gen_override("extended", {
-    indicators = { "j", "k", "l", "h" },
-    active_indicators = { "J", "K", "L", "H" },
-  }),
+  custom_formatter = Harpoonline.gen_override("extended", opts),
 })
 ```
 
-Output A: :anchor:  `j k l -`
+Output A: :anchor:  `j k l ·`
 
-Output B: :anchor:  `j K l -`
+Output B: :anchor:  `j <k> l ·`
 
 #### Use a custom formatter
 
-The following data is kept up-to-date internally to be consumed by formatters:
+The following data is kept up-to-date internally, to be processed by formatters:
 
 ```lua
 ---@class HarpoonLineData
 H.data = {
   --- @type string|nil
-  list_name = nil, -- the name of the list in use
+  list_name = nil, -- the name of the current list
   --- @type number
-  list_length = 0, -- the length of the list
+  list_length = 0, -- the length of the current list
   --- @type number|nil
-  buffer_idx = nil, -- the harpoon index of the current buffer if harpooned
+  buffer_idx = nil, -- the mark of the current buffer if harpooned
 }
 ```
 
@@ -221,15 +231,16 @@ Example:
 local Harpoonline = require("harpoonline")
 Harpoonline.setup({
   custom_formatter = Harpoonline.gen_formatter(
-    function(data, _)
-      return string.format(
+    ---@param data HarpoonLineData
+    ---@return string
+    function(data)
+      return string.format( -- very short, without the length of the harpoon list
         "%s%s%s",
         "➡️ ",
         data.list_name and string.format("%s ", data.list_name) or "",
         data.buffer_idx and string.format("%d", data.buffer_idx) or "-"
       )
-    end,
-    {}
+    end
   ),
 })
 ```
@@ -243,8 +254,7 @@ See the example recipe for NvChad.
 
 ## Harpoon lists
 
-This plugin provides support for working with multiple harpoon lists.
-
+This plugin supports working with multiple harpoon lists.
 The list in use when Neovim is started is assumed to be the default list
 
 The plugin needs to be notified when switching to another list
diff --git a/lua/harpoonline/init.lua b/lua/harpoonline/init.lua
index a2a12aa..7b98d06 100644
--- a/lua/harpoonline/init.lua
+++ b/lua/harpoonline/init.lua
@@ -1,12 +1,11 @@
 -- Module definition ==========================================================
 
--- suitable icons: "󰀱", "", "󱡅"
 local has_harpoon, Harpoon = pcall(require, 'harpoon')
 local _, Extensions = pcall(require, 'harpoon.extensions')
 
 ---@class HarpoonLine
 local Harpoonline = {}
-local H = {}
+local H = {} -- helpers
 
 ---@param config? HarpoonLineConfig
 ---@return HarpoonLine
@@ -24,115 +23,59 @@ end
 
 ---@class HarpoonLineConfig
 Harpoonline.config = {
+  -- suitable icons: "󰀱", "", "󱡅"
   ---@type string|nil
   icon = '󰀱',
 
-  -- Harpoon:list() retrieves the default list: The name of the list is nil.
-  -- The name to display can be configured by using default_list_name
+  -- Harpoon:list() retrieves the default list: The name of that list is nil.
+  -- default_list_name: Configures the display name for the default list.
   ---@type string
   default_list_name = '',
 
   ---@type string
-  formatter = 'extended', -- use a builtin formatter
+  formatter = 'extended', -- short -- use a builtin formatter
 
   ---@type fun():string|nil
-  custom_formatter = nil, -- use this formatter when supplied
+  custom_formatter = nil, -- use this formatter when configured
   ---@type fun()|nil
   on_update = nil, -- optional action to perform after update
 }
 
--- A formatter is a function that transforms the data into a line
--- The first argument is the data, the second argument a table containing options
----@type table<string,function>
+---@class HarpoonlineFormatterConfig
 Harpoonline.formatters = {
-  ---@param data HarpoonLineData
-  ---@param _ any
-  ---@return string
-  short = function(data, _)
-    local icon = H.get_config().icon
-    return string.format(
-      '%s%s[%s%d]',
-      icon and string.format('%s ', icon) or '',
-      data.list_name and data.list_name or H.get_config().default_list_name,
-      data.buffer_idx and string.format('%s|', data.buffer_idx) or '',
-      data.list_length
-    )
-  end,
-
-  ---@param data HarpoonLineData
-  ---@param opts table
-  ---@return string
-  extended = function(data, opts)
-    --          ╭─────────────────────────────────────────────────────────╮
-    --          │             credits letieu/harpoon-lualine              │
-    --          ╰─────────────────────────────────────────────────────────╯
-    local icon = H.get_config().icon
-    local prefix = string.format(
-      '%s%s',
-      icon and string.format('%s ', icon) or '',
-      data.list_name and data.list_name or H.get_config().default_list_name
-    )
-
-    local length = #opts.indicators
-    local status = {}
-    for i = 1, length do
-      local indicator
-      if i > data.list_length then
-        indicator = opts.empty_slot
-      elseif data.buffer_idx and data.buffer_idx == i then
-        indicator = opts.active_indicators[i]
-      else
-        indicator = opts.indicators[i]
-      end
-      table.insert(status, indicator)
-    end
-    return prefix .. ' ' .. table.concat(status, ' ')
-  end,
-}
----@type table<string,table>
-Harpoonline.formatter_opts = {
-  short = {},
-  extended = {
-    indicators = { '1', '2', '3', '4' },
-    active_indicators = { '[1]', '[2]', '[3]', '[4]' },
-    empty_slot = '-',
-  },
+  extended = function() return { formatter = H.builtin_extended, opts = H.builtin_options_extended } end,
+  short = function() return { formatter = H.builtin_short, opts = H.builtin_options_short } end,
 }
 
 -- Module functionality =======================================================
 
--- Given a formatter function, return a wrapper function to be invoked
--- by statuslines.
--- The wrapper calls this function with two arguments:
---   - data: The internal cache from this module
---   - opts: The formatter specific options
+-- Given a formatter function, return a wrapper function that can be invoked
+-- by consumers.
 ---@param formatter fun(data: HarpoonLineData, opts?: table):string
----@param opts table
+---@param opts? table
 ---@return function
 Harpoonline.gen_formatter = function(formatter, opts)
-  return function() return formatter(H.data, opts) end
+  return opts and function() return formatter(H.data, opts) end or function() return formatter(H.data) end
 end
 
--- Given a builtin formatter, return a wrapper function to be invoked
--- by statuslines. The options are merged with the default options
+-- Calls gen_formatter using a builtin formatter identified by name
+-- Merges the options with the default options of that formatter
 --
--- If the builtin is not a valid builtin formatter, "extended" will be used
----@param builtin string
+-- If name is not valied, "extended" will be used
+---@param name string
 ---@param opts table
 ---@return function
-Harpoonline.gen_override = function(builtin, opts)
-  local is_valid = vim.tbl_contains(vim.tbl_keys(Harpoonline.formatters), builtin)
-  local key = is_valid and builtin or 'extended'
-  opts = vim.tbl_deep_extend('force', Harpoonline.formatter_opts[key], opts)
-  return Harpoonline.gen_formatter(Harpoonline.formatters[key], opts)
+Harpoonline.gen_override = function(name, opts)
+  local config = H.get_builtin_config(name, opts)
+  return Harpoonline.gen_formatter(config.formatter, config.opts)
 end
 
 -- Return true is the current buffer is harpooned, false otherwise
--- Useful for extra highlighting code
+-- Useful for extra highlighting
 ---@return boolean
 Harpoonline.is_buffer_harpooned = function() return H.data.buffer_idx and true or false end
 
--- The function to be used by statuslines
+-- The function to be used by consumers
 ---@return string
 Harpoonline.format = function()
   if not H.cached_result then H.cached_result = H.formatter and H.formatter() or '' end
@@ -147,17 +90,31 @@ H.default_config = vim.deepcopy(Harpoonline.config)
 ---@class HarpoonLineData
 H.data = {
   --- @type string|nil
-  list_name = nil, -- the name of the list in use
+  list_name = nil, -- the name of the current list
   --- @type number
-  list_length = 0, -- the length of the list
+  list_length = 0, -- the length of the current list
   --- @type number|nil
-  buffer_idx = nil, -- the harpoon index of the current buffer if harpooned
+  buffer_idx = nil, -- the mark of the current buffer if harpooned
 }
 -- @type string|nil
 H.cached_result = nil
+
 ---@type fun():string|nil
 H.formatter = nil
 
+---@class HarpoonlineBuiltinOptionsShort
+H.builtin_options_short = {
+  inner_separator = '|',
+}
+
+---@class HarpoonlineBuiltinOptionsExtended
+H.builtin_options_extended = {
+  indicators = { '1', '2', '3', '4' },
+  active_indicators = { '[1]', '[2]', '[3]', '[4]' },
+  empty_slot = '·', -- interpunct, or middledot,
+  more_marks_indicator = '…', -- horizontal elipsis
+}
+
 -- Helper functionality =======================================================
 
 ---@param config? HarpoonLineConfig
@@ -175,17 +132,16 @@ H.setup_config = function(config)
 end
 
 -- Sets the final config to use.
--- If config.custom_formatter is supplied, this will be the final formatter.
+-- If config.custom_formatter is configured, this will be the final formatter.
 -- Otherwise, use builtin config.formatter if its valid.
--- Fallback to the "extended" formatter if config.formatter is not valid.
+-- Otherwise, fallback to the "extended" builint formatter
 ---@param config HarpoonLineConfig
 H.apply_config = function(config)
   if config.custom_formatter then
     H.formatter = config.custom_formatter
   else
-    local is_valid = vim.tbl_contains(vim.tbl_keys(Harpoonline.formatters), config.formatter)
-    local key = is_valid and config.formatter or 'extended'
-    H.formatter = Harpoonline.gen_formatter(Harpoonline.formatters[key], Harpoonline.formatter_opts[key])
+    local formatter_config = H.get_builtin_config(config.formatter)
+    H.formatter = Harpoonline.gen_formatter(formatter_config.formatter, formatter_config.opts)
   end
   Harpoonline.config = config
 end
@@ -193,6 +149,21 @@ end
 ---@return HarpoonLineConfig
 H.get_config = function() return Harpoonline.config end
 
+-- Retuns the function and the options of the builtin config
+-- identified by name.
+-- The options are merged with the default options of the formatter.
+---@param name string
+---@param opts? table
+---@return table
+H.get_builtin_config = function(name, opts)
+  local is_valid = vim.tbl_contains(vim.tbl_keys(Harpoonline.formatters), name)
+  local key = is_valid and name or 'extended'
+  local result = Harpoonline.formatters[key]()
+
+  if opts then result.opts = vim.tbl_deep_extend('force', result.opts, opts) end
+  return result
+end
+
 -- Update the data on each BufEnter event
 -- Update the name of the list on custom event HarpoonSwitchedList
 H.create_autocommands = function()
@@ -217,7 +188,7 @@ end
 ---@return HarpoonList
 H.get_list = function() return Harpoon:list(H.data.list_name) end
 
--- If the current buffer is harpooned, return the index of the mark in harpoon's list
+-- If the current buffer is harpooned, return the index of the harpoon mark
 -- Otherwise, return nil
 ---@return number|nil
 H.buffer_idx = function()
@@ -232,7 +203,7 @@ end
 
 -- Update the data when the user adds to or removes from a list.
 -- Needed because those actions can be done without leaving the buffer.
--- All other update scenarios are covered by listening toe the BufEnter event.
+-- All other update scenarios are covered by listening to the BufEnter event.
 H.create_extensions = function()
   Harpoon:extend({
     [Extensions.event_names.ADD] = function()
@@ -255,10 +226,57 @@ end
 -- Performs action on_update if present
 H.update = function()
   H.update_data()
-  H.cached_result = nil -- format should recompute
+  H.cached_result = nil -- the format function should recompute
 
   local on_update = H.get_config().on_update
   if on_update then on_update() end
 end
 
+---@param data HarpoonLineData
+---@param opts HarpoonlineBuiltinOptionsShort
+---@return string
+H.builtin_short = function(data, opts)
+  local icon = H.get_config().icon
+  return string.format(
+    '%s%s[%s%d]',
+    icon and string.format('%s ', icon) or '',
+    data.list_name and data.list_name or H.get_config().default_list_name,
+    data.buffer_idx and string.format('%s%s', data.buffer_idx, opts.inner_separator) or '',
+    data.list_length
+  )
+end
+
+---@param data HarpoonLineData
+---@param opts HarpoonlineBuiltinOptionsExtended
+---@return string
+H.builtin_extended = function(data, opts)
+  --          ╭─────────────────────────────────────────────────────────╮
+  --          │             credits letieu/harpoon-lualine              │
+  --          ╰─────────────────────────────────────────────────────────╯
+  local icon = H.get_config().icon
+  local prefix = string.format(
+    '%s%s',
+    icon and string.format('%s ', icon) or '',
+    data.list_name and data.list_name or H.get_config().default_list_name
+  )
+
+  local nr_of_indicators = #opts.indicators
+  local indicator
+  local status = {}
+  for i = 1, nr_of_indicators do
+    if i > data.list_length then
+      indicator = opts.empty_slot
+    elseif data.buffer_idx and data.buffer_idx == i then
+      indicator = opts.active_indicators[i]
+    else
+      indicator = opts.indicators[i]
+    end
+    table.insert(status, indicator)
+  end
+  if (data.list_length > nr_of_indicators) and opts.more_marks_indicator then
+    table.insert(status, opts.more_marks_indicator)
+  end
+  return prefix .. ' ' .. table.concat(status, ' ')
+end
+
 return Harpoonline