diff --git a/markdown.dtx b/markdown.dtx
index 47b3a482d..54423b63a 100644
--- a/markdown.dtx
+++ b/markdown.dtx
@@ -14388,7 +14388,9 @@ following text:
 %    \end{macrocode}
 % \begin{markdown}
 % The macro is exposed in the interface, so that the user can create their own
-% markdown environments.
+% markdown environments. Due to the way the arguments are passed to Lua (see
+% Section <#sec:directlua>), the first argument may not contain the
+% string `]]` (regardless of the category code of the bracket symbol (`]`)).
 %
 % The \mdef{markdownMode} macro specifies how the plain \TeX{} implementation
 % interfaces with the Lua interface. The valid values and their meaning are
@@ -21892,10 +21894,245 @@ end
 % \par
 % \begin{markdown}
 %
+% The following two sections of the implementation have been deprecated and
+% will be removed in Markdown 3.0.0. The code that corresponds to
+% \mref{markdownMode} value of `4` will be the one and only implementation.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\ifnum\markdownMode=4\relax
+\markdownInfo{Using mode 4: The lt3luabridge package}%
+\input lt3luabridge\relax
+\def\markdownLuaExecute{\luabridgeExecute}%
+\else
+%    \end{macrocode}
+% \begin{markdown}
+%
+%### Lua Shell Escape Bridge {#luabridge}
+%
+% The following \TeX{} code is intended for \TeX{} engines that do not provide
+% direct access to Lua, but expose the shell of the operating system. This
+% corresponds to the \mref{markdownMode} values of `0` and `1`.
+%
+% The \mref{markdownLuaExecute} macro defined here and in Section
+% <#sec:directlua> are meant to be indistinguishable to the remaining code.
+%
+% The package assumes that although the user is not using the Lua\TeX{} engine,
+% their \TeX{} distribution contains it, and uses shell access to produce and
+% execute Lua scripts using the \TeX{}Lua interpreter~[@luatex17, Section
+% 3.1.1].
+%
+\ifnum\markdownMode<2\relax
+\ifnum\markdownMode=0\relax
+  \markdownWarning{Using mode 0: Shell escape via write18
+                   (deprecated, to be removed in Markdown 3.0.0)}%
+\else
+  \markdownWarning{Using mode 1: Shell escape via os.execute
+                   (deprecated, to be removed in Markdown 3.0.0)}%
+\fi
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+% The \mdef{markdownExecuteShellEscape} macro contains the numeric value indicating
+% whether the shell access is enabled (`1`), disabled (`0`), or restricted
+% (`2`).
+%
+% Inherit the value of the the \mref{pdfshellescape} (Lua\TeX{}, \Hologo{pdfTeX})
+% or the \mref{shellescape} (\Hologo{XeTeX}) commands. If neither of these
+% commands is defined and Lua is available, attempt to access the
+% \luamref{status.shell_escape} configuration item.
+%
+% If you cannot detect, whether the shell access is enabled, act as if it were.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\ifx\pdfshellescape\undefined
+  \ifx\shellescape\undefined
+    \ifnum\markdownMode=0\relax
+      \def\markdownExecuteShellEscape{1}%
+    \else
+      \def\markdownExecuteShellEscape{%
+        \directlua{tex.sprint(status.shell_escape or "1")}}%
+    \fi
+  \else
+    \let\markdownExecuteShellEscape\shellescape
+  \fi
+\else
+  \let\markdownExecuteShellEscape\pdfshellescape
+\fi
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+% The \mdef{markdownExecuteDirect} macro executes the code it has received as
+% its first argument by writing it to the output file stream 18, if Lua is
+% unavailable, or by using the Lua \luamref{os.execute} method otherwise.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\ifnum\markdownMode=0\relax
+  \def\markdownExecuteDirect#1{\immediate\write18{#1}}%
+\else
+  \def\markdownExecuteDirect#1{%
+    \directlua{os.execute("\luaescapestring{#1}")}}%
+\fi
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+% The \mdef{markdownExecute} macro is a wrapper on top of
+% \mref{markdownExecuteDirect} that checks the value of
+% \mref{markdownExecuteShellEscape} and prints an error message if the shell is
+% inaccessible.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\def\markdownExecute#1{%
+  \ifnum\markdownExecuteShellEscape=1\relax
+    \markdownExecuteDirect{#1}%
+  \else
+    \markdownError{I can not access the shell}{Either run the TeX
+      compiler with the --shell-escape or the --enable-write18 flag,
+      or set shell_escape=t in the texmf.cnf file}%
+  \fi}%
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+% The \mdef{markdownLuaExecute} macro executes the Lua code it has received as
+% its first argument. The Lua code may not directly interact with the \TeX{}
+% engine, but it can use the \luamref{print} function in the same manner it
+% would use the \luamref{tex.print} method.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\begingroup
+%    \end{macrocode}
+% \begin{markdown}
+% Swap the category code of the backslash symbol and the pipe symbol, so that
+% we may use the backslash symbol freely inside the Lua code.
+% \end{markdown}
+%  \begin{macrocode}
+  \catcode`|=0%
+  \catcode`\\=12%
+  |gdef|markdownLuaExecute#1{%
+%    \end{macrocode}
+% \begin{markdown}
+% Create the file \mref{markdownOptionHelperScriptFileName} and fill it with the
+% input Lua code prepended with \pkg{kpathsea} initialization, so that Lua
+% modules from the \TeX{} distribution are available.
+% \end{markdown}
+%  \begin{macrocode}
+    |immediate|openout|markdownOutputFileStream=%
+      |markdownOptionHelperScriptFileName
+    |markdownInfo{Writing a helper Lua script to the file
+      "|markdownOptionHelperScriptFileName"}%
+    |immediate|write|markdownOutputFileStream{%
+      local ran_ok, error = pcall(function()
+        local ran_ok, kpse = pcall(require, "kpse")
+        if ran_ok then kpse.set_program_name("luatex") end
+        #1
+      end)
+%    \end{macrocode}
+% \begin{markdown}
+% If there was an error, use the file \mref{markdownOptionErrorTempFileName} to
+% store the error message.
+% \end{markdown}
+%  \begin{macrocode}
+      if not ran_ok then
+        local file = io.open("%
+          |markdownOptionOutputDir
+          /|markdownOptionErrorTempFileName", "w")
+        if file then
+          file:write(error .. "\n")
+          file:close()
+        end
+        print('\\markdownError{An error was encountered while executing
+               Lua code}{For further clues, examine the file
+               "|markdownOptionOutputDir
+               /|markdownOptionErrorTempFileName"}')
+      end}%
+    |immediate|closeout|markdownOutputFileStream
+%    \end{macrocode}
+% \begin{markdown}
+% Execute the generated \mref{markdownOptionHelperScriptFileName} Lua script using
+% the \TeX{}Lua binary and store the output in the
+% \mref{markdownOptionOutputTempFileName} file.
+% \end{markdown}
+%  \begin{macrocode}
+    |markdownInfo{Executing a helper Lua script from the file
+      "|markdownOptionHelperScriptFileName" and storing the result in the
+      file "|markdownOptionOutputTempFileName"}%
+    |markdownExecute{texlua "|markdownOptionOutputDir
+      /|markdownOptionHelperScriptFileName" > %
+      "|markdownOptionOutputDir
+      /|markdownOptionOutputTempFileName"}%
+%    \end{macrocode}
+% \begin{markdown}
+% \mref{input} the generated \mref{markdownOptionOutputTempFileName} file.
+% \end{markdown}
+%  \begin{macrocode}
+    |input|markdownOptionOutputTempFileName|relax}%
+|endgroup
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+%### Direct Lua Access {#directlua}
+%
+% The following \TeX{} code is intended for \TeX{} engines that provide
+% direct access to Lua (Lua\TeX{}). The macro \mref{markdownLuaExecute} defined
+% here and in Section <#sec:luabridge> are meant to be indistinguishable to
+% the remaining code. This corresponds to the \mref{markdownMode} value of `2`.
+%
+% \end{markdown}
+%  \begin{macrocode}
+\else
+  \markdownWarning{Using mode 2: Direct Lua access
+                   (deprecated, to be removed in Markdown 3.0.0)}%
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
+% The direct Lua access version of the \mref{markdownLuaExecute} macro is defined
+% in terms of the \mref{directlua} primitive. The \luamref{print} function is set as
+% an alias to the \luamref{tex.print} method in order to mimic the behaviour of the
+% \mref{markdownLuaExecute} definition from Section <#sec:luabridge>,
+%
+% \end{markdown}
+%  \begin{macrocode}
+\begingroup
+%    \end{macrocode}
+% \begin{markdown}
+% Swap the category code of the backslash symbol and the pipe symbol, so that
+% we may use the backslash symbol freely inside the Lua code.
+% \end{markdown}
+%  \begin{macrocode}
+  \catcode`|=0%
+  \catcode`\\=12%
+  |gdef|markdownLuaExecute#1{%
+    |directlua{%
+      local function print(input)
+        local output = {}
+        for line in input:gmatch("[^\r\n]+") do
+          table.insert(output, line)
+        end
+        tex.print(output)
+      end
+      #1
+    }%
+  }%
+|endgroup
+\fi\fi
+%    \end{macrocode}
+% \par
+% \begin{markdown}
+%
 %### Typesetting Markdown
 %
-% The \mref{markdownInput} macro uses the \mref{luabridgeExecute} macro from
-% the \pkg{l3luabridge} package to convert the contents of the file whose
+% The \mref{markdownInput} macro uses an implementation of the
+% \mref{markdownLuaExecute} macro to convert the contents of the file whose
 % filename it has received as its single argument from markdown to plain
 % \TeX{}.
 %
@@ -21949,7 +22186,7 @@ end
       |openin|markdownInputFileStream#1
       |closein|markdownInputFileStream
       |markdownPrepareLuaOptions
-      |luabridgeExecute{%
+      |markdownLuaExecute{%
         |markdownPrepare
         local file = assert(io.open("#1", "r"),
           [[could not open file "#1" for reading]])