Within the shown MWE, I need to avoid breaking the table in midst of merged rows. However, is there a way to do this automatically without using the approach described in
Since I will have to manually adjust the location of the command
\pagebreak
On each time I modify the document content which may result in modifying table location and thus shifting position of rows
Secondly, the horizontal lines do not extend till the end of the table, is there a fix??
Thirdly, there is interference between the row repeated at the top of each page and the actual content of the first row
\documentclass[a4paper,12pt,twoside]{book}
\usepackage[a4paper,top=2.5cm,bottom=2.5cm,margin=2.5cm,bindingoffset=0.5cm]{geometry}
\usepackage[bidi=basic,layout=lists.tabular]{babel}
\babelfont[english]{rm}{Times New Roman}
\usepackage[table]{xcolor}
\usepackage{tabu,multirow}
\usepackage{array}
\newcolumntype{?}[1]{!{\vrule width #1}}
\usepackage{booktabs}
\setlength{\belowrulesep}{0pt}
\setlength{\belowbottomsep}{0pt}
\setlength{\aboverulesep}{0pt}
\setlength{\belowrulesep}{0pt}
\setlength{\abovetopsep}{0pt}
\usepackage{longtable}
\usepackage{makecell}
\usepackage{boldline}
\usepackage{hhline}
\usepackage{rotating}
\begin{document}
\begin{longtable}{?{1mm}>{\centering\arraybackslash}m{0.2\textwidth}|c|c|c|c|c?{1mm}}
\toprule[1mm]
& \multicolumn{2}{c?{1mm}}{\textbf{U.S. CUSTOMARY UNITS}} & & \multicolumn{2}{c?{1mm}}{\textbf{Equivlent SI Unit}} \\
\cmidrule[1.25pt]{2-3}
\cmidrule[1.25pt]{5-6}
\multirow{-2}{*}{\textbf{Type of quantity}} & \textbf{Unit} & \textbf{Abbreviation} &
\multirow{-2}{*}{\textbf{Multiplication factor}} & \textbf{Unit} & \textbf{Abbreviation} \\
\Xhline{1.5pt}
\endfirsthead
\toprule[1mm]
& \multicolumn{2}{c?{1mm}}{\textbf{U.S. CUSTOMARY UNITS}} & & \multicolumn{2}{c?{1mm}}{\textbf{Equivlent SI Unit}} \\
\cmidrule[1.25pt]{2-3}
\cmidrule[1.25pt]{5-6}
\multirow{-2}{*}{\textbf{Type of quantity}} & \textbf{Unit} & \textbf{Abbreviation} &
\multirow{-2}{*}{\textbf{Multiplication factor}} & \textbf{Unit} & \textbf{Abbreviation} \\
\Xhline{1.5pt}
\endhead
\multicolumn{6}{c}{Continued}\\
\bottomrule
\endfoot
\bottomrule[1mm]
\endlastfoot
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
\multirow{-3}{*}{\textbf{Mass}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-3}{*}{m/s} & \multirow{-3}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
\multirow{-3}{*}{\textbf{Mass}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-3}{*}{m/s} & \multirow{-3}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{white}
\multirow{-3}{*}{\textbf{Mass}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-3}{*}{m/s} & \multirow{-3}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
& cu & cu & slug**=$\frac{Ib.sec^2}{ft}$ & & \\
\cmidrule[0.5pt]{2-4}
\rowcolor{gray!25}
\multirow{-4}{*}{\textbf{Length}}& meter* & m & slug**=$\frac{Ib.sec^2}{ft}$ & \multirow{-4}{*}{m/s} & \multirow{-4}{*}{m/s} \\
\Xhline{1pt}
\end{longtable}
\end{document}
\\*
vs.\\
approach also mentioned in the linked answer?