%%
%% The LaTeX Companion, 3ed
%%
%% Example 12-1-9 on page II-229 in "The world of (Latin) math alphabets".
%%
%% 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{159.0pt}

  \AddToHook{begindocument/end}{%      % save some space in the example
    \setlength\abovedisplayshortskip{4pt}%
    \setlength\belowdisplayskip{0pt}%
    \setlength\belowdisplayshortskip{0pt}}

  \typeout{This example requires commercial fonts that are not provided^^J%
           with a free LaTeX installation but must be obtained separately.}
%%
%StartShownPreambleCommands
\DeclareMathAlphabet\mathcal{T1}{hlcw}{m}{it}
\DeclareMathAlphabet\mathscr{T1}{Almndr-OsF}{m}{it}
%StopShownPreambleCommands

\begin{document}
\[ A_B \neq \mathscr{A}_\mathscr{B}
             \neq \mathcal{A}_\mathcal{B}          \]
\[ \mathcal{ABCDEFGHI} \dots \mathscr{PQRSTUVWXYZ} \]
\end{document}