The "shorttitle", that is the text within the last { } in the code, appears both in the tcbox and in the tcblist.
But the "short title" often has to be too short to be really understandable so I also have, under the "short title but before the \tcblower, a "long title".
But then the "short title" is unnecessary in the tcbox
So, what I would like is for the "short title" not to show in the tcbox and to show only in the tcblist.
Here is a MWE:
% !TEX TS-program = pdflatexmk
\documentclass[11pt]{book}
%+++++Begin PREAMBLE%+++++Begin PREAMBLE%+++++Begin PREAMBLE%+++++Begin PREAMBLE
%+++++Begin PREAMBLE%+++++Begin PREAMBLE%+++++Begin PREAMBLE%+++++Begin PREAMBLE
\usepackage{relsize} %Set the font size relative to the current font size
\usepackage{titlesec}
\usepackage{etoolbox} %what does it do, why is it here?
\usepackage[dotinlabels]{titletoc}
\usepackage{tcolorbox}%
\usepackage[hypertexnames=false, hyperfootnotes=false]{hyperref}%[pdfborder={0 0 0}] %added hypertextnames=false as per Simon Dispa See https://tex.stackexchange.com/questions/3188/what-does-the-hyperref-option-hypertexnames-do
%=======Begin tcolorbox ---The PACKAGE must be here. The tcolorboxes must be defined after cleveref.
\tcbuselibrary{%Begin load libraries for tcolorbox
skins,%
raster,%
breakable,%
}%End load libraries for tcolorbox
\usepackage{xpatch}
%%% added according to SimonDipsa<<<<<<<<<<<<Modified according to NoteFromSimon
\xpretocmd{\chapter}{% reset counters & add some space in list
\setcounter{PRCstore}{0}%
\setcounter{DMOstore}{0}%
\setcounter{DMOm}{0}%
\setcounter{subDMOm}{0}%
\setcounter{PRCm}{0}%
\setcounter{subPRCm}{0}%
\addtocontents{PRC}{\protect\addvspace{10pt}}%
\addtocontents{DMO}{\protect\addvspace{10pt}}}%
{}{}%% <<<<<<<<<<<<<<<<<<<<<<<<<<<
\usepackage{cleveref}% should be the last package
\newcounter{PRC}%[chapter] % \renewcommand{\thePRC}{\number\numexpr\value{PRC}+1\relax}% Display PRC+1
\newcounter{PRCm}%
\newcounter{PRCstore}%
\newcounter{subPRCm}% a b c .
\newcounter{subPRCpass}%% on off
\newcounter{DMO}%[chapter] % }% Display DMO+1
\newcounter{DMOm}%
\newcounter{DMOstore}%
\newcounter{subDMOm}% a b c
\newcounter{subDMOpass}%% on off
%============== Begin definition of PROCEDURE
\newtcolorbox[%
auto counter,
number freestyle={\noexpand\thechapter.\noexpand\arabic{PRC}},
number within=chapter,%
list inside= PRC,%creates the list under tcblistof.
crefname={\textsc{procedure}}{\textsc{procedures}},%
Crefname={\textsc{Procedure}}{\textsc{Procedures}}%
]%endForReferences
{%begin name environment
PROCEDURE%
}%end name Environment
[2][]{%Whatever that is
code=%
\setcounter{PRC}{\value{PRCstore}}%
\setcounter{subPRCpass}{0}%
\addtocounter{PRC}{1} ,
after title=%
\setcounter{PRCstore}{\value{PRC}},
enhanced,
breakable,
detach title,
attach title to upper=~,%
lower separated=true,
bicolor,%
% boxrule=1mm,%
colframe=black,%controls both the background color for the top and the frame of the bottom
colback=cyan,%This is the background color below the title.
colbacklower=yellow,%This is the background color below the title.
top=0pt,
bottom=0pt,
boxsep=5pt,% Sets a common padding between text and frame of box. Added to left, right, top, bottom, and middle.
outer arc=2mm,%when line is thick. Else, can just use arc.
fontupper=\sffamily,
fontlower=\sffamily,
coltitle=black,%
nameref={#2},%
list entry={\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
title={\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
#1%
}%
%============== End definition of PROCEDURE
%============== Begin definition of PROCEDUREsub
\newtcolorbox[%
%use counter= PRC,
auto counter,
number within=chapter,
number freestyle={\noexpand\thechapter.\noexpand\arabic{PRCm}\noexpand\alph{subPRCm}},%
list inside= PRC,%creates the list under tcblistof.
crefname={\textsc{procedure}}{\textsc{procedures}},%
Crefname={\textsc{Procedure}}{\textsc{Procedures}},%
]
{PROCEDUREsub}[2][]{%
code=%
\setcounter{PRCm}{\value{PRCstore}}%
\addtocounter{PRCm}{1}%
\addtocounter{subPRCm}{1},
after title=%
\addtocounter{\tcbcounter}{1} ,
enhanced,
breakable,
detach title,
attach title to upper=~,%
lower separated=true,
bicolor,%
% boxrule=1mm,%
colframe=black,%controls both the background color for the top and the frame of the bottom
colback=cyan,%This is the background color below the title.
colbacklower=yellow,%This is the background color below the title.
top=0pt,
bottom=0pt,
boxsep=5pt,% Sets a common padding between text and frame of box. Added to left, right, top, bottom, and middle.
outer arc=2mm,%when line is thick. Else, can just use arc.
fontupper=\sffamily,
fontlower=\sffamily,
coltitle=black,%
nameref={#2},%
list entry= {\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
title= {\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
#1%
}%
%================ End definition of PROCEDUREsub
%=============== Begin definition of PROCEDUREend
\newtcolorbox[%
%%use counter= PRCm,
auto counter,
number within=chapter,
number freestyle={\noexpand\thechapter.\noexpand\arabic{PRCm}\noexpand\alph{subPRCm}},%
list inside= PRC,%creates the list under tcblistof.
crefname={\textsc{procedure}}{\textsc{procedures}},%
Crefname={\textsc{Procedure}}{\textsc{Procedures}},%
]
{PROCEDUREend}[2][]{%
code=%
\setcounter{PRCm}{\value{PRCstore}}%
\addtocounter{PRCm}{1}%
\addtocounter{subPRCm}{1}%
\setcounter{subPRCpass}{1} ,
after title=%
\setcounter{PRCstore}{\value{PRCm}}%
\setcounter{subPRCm}{0},
enhanced,
breakable,
detach title,
attach title to upper=~,%
lower separated=true,
bicolor,%
% boxrule=1mm,%
colframe=black,%controls both the background color for the top and the frame of the bottom
colback=cyan,%This is the background color below the title.
colbacklower=yellow,%This is the background color below the title.
top=0pt,
bottom=0pt,
boxsep=5pt,% Sets a common padding between text and frame of box. Added to left, right, top, bottom, and middle.
outer arc=2mm,%when line is thick. Else, can just use arc.
fontupper=\sffamily,
fontlower=\sffamily,
coltitle=black,%
nameref={#2},%
list entry={\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
title={\textbf{P\smaller{ROCEDURE}}\hspace{1.5mm}\textbf{\thetcbcounter}\hspace{2mm} #2},%
#1%
}%
%=========== End definition of PROCEDUREend
%+++++End PREAMBLE+++++End PREAMBLE+++++End PREAMBLE+++++End PREAMBLE
%+++++End PREAMBLE+++++End PREAMBLE+++++End PREAMBLE+++++End PREAMBLE
\begin{document}
%========================================== Begin PROCEDURE
\begin{PROCEDURE}[label={PRC:1-1}]{Short Title 1}
Long Title 1
\tcblower
Text of PROCEDURE 1.
\end{PROCEDURE}
%========================================== End PROCEDURE
%========================================== Begin PROCEDURErsub
\begin{PROCEDUREsub}[label={PRC:1-1}]{Short Title 2a}
Long Title 2a
\tcblower
Text of PROCEDURE 2a
\end{PROCEDUREsub}
%========================================== End PROCEDURErsub
%========================================== Begin PROCEDUREend
\begin{PROCEDUREend}[label={PRC:1-1}]{Short Title 2b}
Long Title 2b
\tcblower
Text of PROCEDURE 2b
\end{PROCEDUREend}
%========================================== End PROCEDUREend
\tcblistof[\chapter]{PRC}{List of Procedures}%
\end{document}
and here is a picture
