# How to make center of line mark in proofreading?

MWE

\documentclass[12pt]{article}
\usepackage{color}
\usepackage{amssymb}
\begin{document}
{\color{red}{$\sqsupset$}}a{\color{red}{$\sqsubset$}}
\end{document}


My purpose is to do it with tikz. Can you help me fix it?

I don't really get why you want to do this in TikZ, you have a perfectly fine symbol right there, but here you go:

\documentclass{article}
\usepackage{tikz}
\newcommand\centerofline[1]{%
\tikz\draw[red] (0,1ex) -| (1ex,0) -- (0,0);%
\kern.2ex\relax
#1%
\kern.2ex\relax
\tikz\draw[red] (1ex,1ex) -| (0,0) -- (1ex,0);%
}
\begin{document}

\small\centerofline{a}

\normalsize\centerofline{a}

\large\centerofline{a}

\Large\centerofline{a}

\end{document}