答案1
不确定你为什么不想要更高级别的包,但它在这里:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\[
\newcommand{\ext}[1]{% a one shot command for this display
\hphantom{\scriptstyle#1}\bigg|{\scriptstyle#1}%
}
\begin{array}{@{}c@{}}
L \\
\ext{e} \\
L^{T\vphantom{\big|}} \\
\ext{f} \\
L^{D\vphantom{\big|}} \\
\ext{g} \\
K
\end{array}
\]
\end{document}