# Use different chapter title in TOC, in the first chapter page, and in header

Say I have two titles t1 and t2 for a chapter. I want to show t1 in TOC, and t2 in the first chapter page as well as the in the header.

I use \chapter[t1]{t2} which works for TOC and the first chapter page. However the header shows t1 instead of t2. Is there a way to enforce t2 in the header?

Thanks.

With memoir, the syntax for \chapter and \section is extended:

\chapter[toc-title][head-title]{title}


If only one argument is used, the same input is used for the TOC and the header, so you want

\chapter[t1][t2]{t2}


Similarly for \section.

Perhaps you're interested in an easier interface. I define the commands \Chapter and \Section. If called like

\Chapter{Title}


then the behavior is the same as \chapter{title}. But you can call

\Chapter[toc=Title for TOC]{Title}


and the title for headers will be “Title”, while in the TOC you'll get what's stated. The third way of calling it is

\Chapter[toc=Title for TOC,head=Title for head]{Title}


for specifying the three elements independently. Here's a full example.

\documentclass{memoir}
\usepackage{xparse}

\usepackage{kantlipsum} % just for the example

\ExplSyntaxOn
% set up the keys
\keys_define:nn { tmv/titles }
{
toc  .tl_set:N = \l_tmv_titles_toc_tl,
}

% user level commands
\NewDocumentCommand{\Chapter}{ O{} m }
{
\tmv_set_titles:nn { #1 } { #2 }
\tmv_division:VVnN \l_tmv_titles_toc_tl \l_tmv_titles_head_tl { #2 } \chapter
}

\NewDocumentCommand{\Section}{ O{} m }
{
\tmv_set_titles:nn { #1 } { #2 }
\tmv_division:VVnN \l_tmv_titles_toc_tl \l_tmv_titles_head_tl { #2 } \section
}

% auxiliary command for setting the keys
\cs_new_protected:Npn \tmv_set_titles:nn #1 #2
{
\keys_set:nn { tmv/titles }
{
toc = { #2 },
#1
}
}

% the command that calls either \chapter or \section
\cs_new_protected:Npn \tmv_division:nnnN #1 #2 #3 #4
{
#4[#1][#2]{#3}
}
\cs_generate_variant:Nn \tmv_division:nnnN { VV }
\ExplSyntaxOff

\begin{document}
\frontmatter
\tableofcontents*

\mainmatter
\Chapter{Unique title}
\Section{Unique section title}
\kant

\Chapter[toc=Title for TOC]{Title also for head}
\Section[toc=Title for TOC]{Title also for head}
\kant