%%
%% The LaTeX Companion, 3ed
%%
%% Example 2-4-5 on page I-82 in "Providing your own reference commands".
%%
%% 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{88.2009pt}
\setlength\textheight{10\baselineskip}
\sloppy
\pagestyle{origplain}

%StartShownPreambleCommands
\usepackage[nospace]{varioref}
\newcommand\veqns[2]{the equation%
  \vpagerefcompare{#1}{#2}%
    {s (\ref{#1})}%
    {  (\ref{#1}) \vpageref{#1}}%
  \space and (\ref{#2}) \vpageref{#2}}
%StopShownPreambleCommands

\begin{document}
Test: \veqns{A}{B}. \par Test: \veqns{A}{C}.
\begin{equation} a=b \label{A}\end{equation}
\begin{equation} b=c \label{B}\end{equation}
\newpage
Test: \veqns{A}{B}. \par Test: \veqns{A}{C}.
\par  We force eq.~\ref{C} to the next page!
\newpage % for eq. to next page
\begin{equation} c=a \label{C}\end{equation}
\end{document}