Three-Line Table Guide

This guide defines the standard for professional academic tables using the "three-line" (booktabs) convention. All table-related checks and generation follow these rules.

Three-Line Table Standard

A three-line table has exactly three horizontal rules and no vertical lines:

1. Top rule (\toprule): above column headers
2. Mid rule (\midrule): below column headers, above data rows
3. Bottom rule (\bottomrule): below the last data row

Anti-Patterns (must flag)

• Vertical lines (| in column spec, \vline, \hline with |)
• Internal horizontal lines (\hline or \cline between data rows, except for grouping sub-headers)
• Using \hline instead of booktabs commands
• Missing \usepackage{booktabs} in preamble

Minimal Correct Example

\begin{table}[t]
  \caption{Comparison of model accuracy (\%).}
  \label{tab:accuracy}
  \centering
  \begin{tabular}{lSSS}
    \toprule
    Model & {Precision} & {Recall} & {F1} \\
    \midrule
    Baseline   & 85.3 & 82.1 & 83.7 \\
    Ours       & \textbf{91.2} & \textbf{89.5} & \textbf{90.3} \\
    \bottomrule
  \end{tabular}
\end{table}

Decimal Alignment

Use the siunitx package S column type to align numbers by decimal point:

\usepackage{siunitx}
\sisetup{detect-weight, mode=text}
% Column spec: {l S[table-format=2.1] S[table-format=2.1]}
% Wrap non-numeric headers in braces: {Precision}

When siunitx is unavailable, right-align numeric columns with r and ensure consistent decimal places manually.

Statistical Significance Markers

Use superscript symbols with footnote definitions in the table note:

Symbol	Meaning
*	p < 0.05
**	p < 0.01
***	p < 0.001
n.s.	not significant

Place significance markers immediately after the value: 91.2***.

Number Precision Rules

Data type	Precision	Example
Percentage	1 decimal place	85.3%
Mean ± SD	2 decimal places	3.14 ± 0.05
p-value	3 significant figures	0.0032
Correlation coefficient	2-3 decimal places	0.87
Large counts	No decimals	1,024

Precision must be consistent within each column. Mixed precision in the same column is a warning.

Caption and Note Placement

• Caption: above the table (\caption{...} before \begin{tabular})
• Label: immediately after caption (\label{tab:...})
• Table note: below the table, starting with "Note." (English) or "注：" (Chinese)

Table note format:

\begin{tablenotes}
  \small
  \item Note. Bold values indicate best performance.
  \item * $p < 0.05$; ** $p < 0.01$; *** $p < 0.001$.
\end{tablenotes}

Or use \par\vspace{2pt}{\footnotesize Note. ...} after \end{tabular} if threeparttable is not loaded.

Bold Best Values

In comparison tables, bold the best value in each column using \textbf{}. When using siunitx S columns, use \bfseries or wrap in {\textbf{91.2}}.

Add direction indicators when the "best" direction is ambiguous:

• ↑ (higher is better): accuracy, recall, F1
• ↓ (lower is better): error rate, latency, loss

Booktabs Package Requirements

The booktabs package must be loaded for \toprule, \midrule, \bottomrule. These commands produce variable-weight rules (top/bottom are heavier than mid) for a professional appearance.

Never mix \hline with booktabs commands in the same table.

Word Compatibility Note

When submitting to venues that require .docx, convert the three-line table by:

1. Create a standard table in Word
2. Select the entire table → Borders → No Border
3. Add top border to first row, bottom border to header row, bottom border to last row
4. Result: a three-line table matching the booktabs aesthetic