在缩写的情况下如何使用小型大写字母？

Question

我正在将缩写作为我书中的一部分。示例如下：

\documentclass[12pt,oneside,openany,openbib,draft]{book} 
%\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\usepackage[total={5in, 8in}]{geometry} 
%% 備註   % 對表格的備注只能使用\footnote{text}
\usepackage[ruled]{bigfoot}
\usepackage{tabularx}
\newcounter{footalt}
\def\thefootalt{\fnsymbol{footalt}}
\MakeSortedPerPage{footalt}
\WithSuffix\def\footnotedefault'{\refstepcounter{footalt}
    \Footnotedefault{\thefootalt}}
\usepackage[hang]{footmisc} 


%% Abbreviation
\usepackage{calc}
\usepackage{lipsum}
\makeatletter
\newcommand{\tocfill}{\cleaders\hbox{$\m@th \mkern\@dotsep mu . \mkern\@dotsep mu$}\hfill}
\makeatother
\newcommand{\abbrlabel}[1]{\makebox[3cm][l]{\textbf{#1}\ \tocfill}}
\newenvironment{abbreviations}{\begin{list}{}{\renewcommand{\makelabel}{\abbrlabel}%
            \setlength{\labelwidth}{3cm}\setlength{\leftmargin}{\labelwidth+\labelsep}%
            \setlength{\itemsep}{0pt}}}{\end{list}}



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\chapter{Abbreviations}

\begin{abbreviations}
    \item[PV\textsc{d}] The embedded word of {\it Pramāṇavārttika} in De
    \item[PVe\textsc{m}] The embedded word of {\it Pramāṇavārttika} in M
    \item[PVe\textsc{m}1] The embedded word of {\it Pramāṇavārttika} in M1
\end{abbreviations}

The following is the second part:

[PV\textsc{d}] The embedded word of {\it Pramāṇavārttika} in De

[PVe\textsc{m}] The embedded word of {\it Pramāṇavārttika} in M

[PVe\textsc{m}1] The embedded word of {\it Pramāṇavārttika} in M1

\end{document}

但是\textsc{xxx}命令在缩写条件下不起作用（如第二部分所示）。我该怎么办？