The scope of a node name

Question

From the very first example of a matrix presented in the "Matrix Library" section 57.1 of the TikZ & PGF manual, I expected the following to result in an arrow connecting the "Signatures" cell to the "Transition" cell in the picture.

    \documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix,fit,positioning,arrows}
\begin{document}
\begin{tikzpicture}[every node/.style={draw, anchor=west}] % added anchor=west
\matrix [matrix of nodes,draw=red,column sep=1cm,name=m]
  {
   \node [xshift=1mm] {\textbf {Transition Record}};\\ % added xshift=1mm
   \node [align=left]
      {\textbf{Signatures} \\
       signed by Ted};\\
   \node [align=left] {\textbf{Transition} \\ \(\tau\)};\\
   \node [align=left]
      {\textbf{End State} \\
       \(\mathtt{Alice2}\mid\mathtt{Carol2}\mid\mathtt{Ted}\)};\\
};
\draw[-latex,bend right] (m-2-1.north west) to (m-4-1.south west);
\end{tikzpicture}
\end{document}

This results in the errors:

• Package pgf Error: No shape named m-4-1 is known. ...] (m-2-1.north west) to (m-4-1.south west)
• Package pgf Error: No shape named m-2-1 is known. ...draw[-latex,bend right] (m-2-1.north west)

On the other hand, if I replace the \draw command with

\draw[-latex,bend right] (m.north west) to (m.south west);

I get exactly the arrow I would expect.

Given that the name "m" is known, it is not clear to me why derived names, "m-1-1", "m-2-1", etc. would not be. This is especially the case given the above cited example from the manual. Apart from getting some insight as to why I am unable to reference the "unknown" shape names, I would like to understand the rules regarding the introduction of names and the scopes within which they are available to reference.

Thank you in advance.

Answer 1

There are two types of matrices floating around in TikZ: matrix of nodes and matrix. You are mixing those. If you use matrix of nodes, you do not have to put the \node commands, and the nodes get automatically labeled. If you do a plain matrix, you can keep your node commands but you need to name the nodes yourself. I use both types of matrices in the following code.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix,fit,positioning,arrows}
\begin{document}
\begin{tikzpicture}[every node/.style={draw, anchor=west}] % added anchor=west
\matrix [matrix,draw=red,column sep=1cm,name=m]
  {
   \node [xshift=1mm] {\textbf {Transition Record}};\\ % added xshift=1mm
   \node [align=left] (m-2-1)
      {\textbf{Signatures} \\
       signed by Ted};\\
   \node [align=left] {\textbf{Transition} \\ \(\tau\)};\\
   \node [align=left] (m-4-1)
      {\textbf{End State} \\
       \(\mathtt{Alice2}\mid\mathtt{Carol2}\mid\mathtt{Ted}\)};\\
};
\draw[-latex,bend right] (m-2-1.north west) to (m-4-1.south west);
\end{tikzpicture}

\begin{tikzpicture}[every node/.style={draw, anchor=west}] % added anchor=west
\matrix [matrix of nodes,draw=red,column sep=1cm,name=m,nodes={align=left,text
width=4cm}]
  {
   |[xshift=1mm]| \textbf {Transition Record}\\ % added 
   {\textbf{Signatures} \\
       signed by Ted}\\
   {\textbf{Transition} \\ \(\tau\)}\\
   {\textbf{End State} \\
       \(\mathtt{Alice2}\mid\mathtt{Carol2}\mid\mathtt{Ted}\)}\\
};
\draw[-latex,bend right] (m-2-1.north west) to (m-4-1.south west);
\end{tikzpicture}
\end{document}

Answer 2

edit: sorry i had some problems with uploading correct version of code ... now should be ok

a slightly modified second example in the nice marmot answer. by use of the stackengine package it gives the similar result as his first example:

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{arrows, matrix}
\usepackage{stackengine}

\begin{document}
    \begin{tikzpicture}                         % <---
\matrix (m) [matrix of nodes, draw=red,
         nodes={draw, anchor=west},             % <---
         row sep=-\pgflinewidth]                % <---
  {
   |[xshift=1mm]| \textbf {Transition Record}\\ 
   \shortstack[l]{\textbf{Signatures} \\          % <---
       signed by Ted}\\
   \shortstack[l]{\textbf{Transition} \\          % <---
       \(\tau\)}\\
   \shortstack[l]{\textbf{End State} \\           % <---
       \(\mathtt{Alice2}\mid\mathtt{Carol2}\mid\mathtt{Ted}\)}\\
};
\draw[-latex] (m-2-1.north west) to [bend right] (m-4-1.south west);
    \end{tikzpicture}
\end{document}