Arrows line decoration on the left of paragraph

Question

I'm working on a small package to manage QRH (a sort of checklist for aeronautical purposes). I want to print a line with arrows on the left of the paragraph, possibly with text in the middle, like in the figure:

Currently I'm using siderules of mdframed package, as suggested here, but I'm able to produce only a straight vertical line, without arrows and without text.

Anyone has some idea? :)

Answer 1

tikzmark could be one option:

\documentclass{article}
\usepackage{lipsum}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\begin{document}
\begin{description}
\item[\tikzmark{a}Blabla text here:] \lipsum[1]
\item[\tikzmark{b}Blabla text here:] \lipsum[1]
\end{description}

\tikz[remember picture,<->] \draw[overlay] ([yshift=1ex]pic cs:a) --++(-0.5,0)  |- ([yshift=1ex]pic cs:b) node[midway, pos=0.25, fill=white]{text};
\end{document}

Answer 2

Here I use a macro approach, \connect{text}{lines}, where lines is the multiple of baselineskip to the connecting line. It can be a non-integer if there are added vertical spaces to contend with (e.g., \topskip and such).

Because the decoration is employed using the tabto package, the \connect{}{} macro can be issued at any place on the starting line of the connection.

EDITED to handle negative <lines> argument, which can reach upward. This can be useful to connect to display math, for which \connect is not valid.

\documentclass{article}
\usepackage{stackengine,tabto}
\newlength\tmplen
\setstackEOL{\cr}
\newcommand\connect[2]{%
  \setstackgap{S}{0pt}%
  \tabto*{0in}%
  \setlength\tmplen{\dimexpr#2\baselineskip-\baselineskip}%
  \setlength\tmplen{.5\tmplen}%
  \ifdim\tmplen>0pt\relax
  \smash{\raisebox{2.5pt}{\makebox[0pt][r]{%
    \Shortunderstack[l]{%
      \smash{\raisebox{-2.7pt}{\rarrow}}\cr
      \protect\rule{.5pt}{\tmplen}\cr
      \makebox[0pt]{#1\strut}\cr
      \protect\rule{.5pt}{\tmplen}%
      \smash{\raisebox{-2.4pt}{\rarrow}}\cr
    }%
  }}}%
  \else
    \setlength\tmplen{-\tmplen}%
    \smash{\raisebox{2.5pt}{\makebox[0pt][r]{%
    \Shortstack[l]{%
      \smash{\raisebox{-2.7pt}{\rarrow}}\cr
      \protect\rule{.5pt}{\tmplen}\cr
      \makebox[0pt]{#1\strut}\cr
      \protect\rule{.5pt}{\tmplen}%
      \smash{\raisebox{-2.4pt}{\rarrow}}\cr
    }%
  }}}%
  \fi
  \tabto{\TabPrevPos}%
}
\def\rarrow{$\kern-.7pt{-}\kern-2pt{-}\kern-2pt{\rightarrow}$}
\begin{document}
\noindent\connect{OR}{4}\textbf{Blabla text here}\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
\noindent\textbf{Blabla text here}\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
\noindent\connect{AND}{6}\textbf{Blabla text here}\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
\noindent\textbf{Blabla text here}\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
   Blabla text here\par
\[
  y = mx + b
\]
   Blabla text here\par
   Blabla text here\par
   \noindent \connect{Math!}{-1.8}Blabla text here\par
\end{document}