%%
%% The LaTeX Companion, 3ed
%%
%% Example 6-9-2 on page I-498 in "Formatting the overall table".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{141.0pt}

%StartShownPreambleCommands
\usepackage{keyvaltable}
\NewKeyValTable[backend=tabular,norules,norowbg,
                headformat=\bfseries]
   {cities}{name; country; visited; note: hidden}
%StopShownPreambleCommands

\begin{document}
\begin{KeyValTable}{cities}
  \Row[above=5pt]{country=Germany, name=Mainz, note=...}
  \MidRule[2pt]
  \Row{country=USA, name=New York, visited=yes}
\end{KeyValTable}
\end{document}