Cross-references, citations and footnotes

Labels

\label{key} names the thing it belongs to:

Where the `\label` is	What `\ref{key}` shows
Right after `\section`, `\subsection` or `\subsubsection`	The section number, e.g. `2.1`
In a numbered equation row	The equation number, e.g. `3`
In a `figure`, `table` or `algorithm` with a caption	The float number, e.g. `2`
In a `subfigure` or `subtable`	The float number and the letter, e.g. `2b`
In a numbered theorem-like environment	Its number, e.g. `4`
Anywhere else	The number of the enclosing section, float or sub-float, if there is one

The label also puts an id on the page, and that is where references link to. Keys can contain any characters except }: fig:loss, sec-intro and eq.1 all work.

A label on something unnumbered (a starred section, a float without a caption) still works as a link target, but it has no number, so \ref shows ??, as LaTeX does.

References

Command	Result
`\ref{key}`	`2`
`\eqref{key}`	`(3)`
`\autoref{key}`, `\cref{key}`, `\Cref{key}`	`Figure 2`, `Section 1`, `Equation 3`, `Theorem 4`
`\pageref{key}`, `\nameref{key}`	`2`, the number (there are no pages or names)
`\ref{a,b}`	`1, 2`: several keys at once, each linked

The word that \autoref and \cref put in front comes from the kind of target: Figure, Table, Algorithm, Section, Equation, or the theorem's name, such as Theorem, Lemma or your \newtheorem title. In Chinese documents they are 图, 表, 算法, 节 and 式. \cref and \Cref give the same result, capitalised. A non-breaking space joins the word and the number.

A reference to a label that doesn't exist shows ??. Lint reports it.

Labels can be used before they are defined: all numbers are resolved after the whole document has been rendered.

Clicking a reference

References, citations and footnote marks are ordinary <a href="#…"> links, but the runtime handles clicks on them itself:

the target is scrolled smoothly to the middle of the view;
the target is briefly highlighted (the latex-flash class, coloured by --hx-flash); for an equation, the whole display flashes;
the URL doesn't change, so the back button doesn't have to step through every reference.

With animate: false, or when the reader's system asks for reduced motion, the page jumps without scrolling or flashing.

Target ids are not stable. Each call to parse gives its ids a random prefix (e.g. tex3k9f2a-fig:loss), so that two documents on one page can't clash. Don't link to them from outside the document.

Citations

Diffusion models \cite{ho2020,song2021} generate …
As shown by \citet[Thm.~2]{song2021}, …

\begin{thebibliography}{9}
  \bibitem{ho2020} J. Ho, A. Jain, P. Abbeel. Denoising diffusion probabilistic models. In \emph{NeurIPS}, 2020.
  \bibitem{song2021} Y. Song et al. Score-based generative modeling through SDEs. In \emph{ICLR}, 2021.
\end{thebibliography}

Command	Result
`\cite{a}`	`[1]`
`\cite{a,b}`	`[1, 2]`
`\cite[p.~7]{a}`	`[1, p. 7]`
`\citep`, `\citet`, `\parencite`, `\textcite`, `\autocite`	The same as `\cite` with numbered entries; author–year with natbib labels (below)

Numbers follow the order of the \bibitems, not the order of citation.
Each number links to its entry in the bibliography.
A key without a \bibitem shows the key itself, e.g. [smith99]. Lint reports it.
With two optional arguments (natbib's \citep[see][p.~7]{a}), only the second is shown.
Citation brackets never break across lines. By default they look like plain numbers; set --hx-cite to draw hyperref-style boxes around them (Theming).

The bibliography

thebibliography becomes a numbered list headed "References" (参考文献). The {9} argument (the widest label) is read and dropped. \bibitem[label]{key} is accepted, but entries are always numbered [1], [2], …. The entry text can contain any inline formatting, links and maths.

An entry with a natbib label, \bibitem[Vaswani et~al.(2017)Vaswani, Shazeer, …]{vaswani2017} as BibTeX writes into a .bbl, is author–year: \citet gives "Vaswani et al. (2017)", \citep "(Vaswani et al., 2017)", and such entries have no numbers in the list. Papers lists every form.

A .bib or .bbl file can be given with the options bib and bbl: it replaces \bibliography{…}; see Papers. Without them, \bibliography{refs}, \addbibresource and \printbibliography are ignored. Write the entries into the document. HaTeX.Bib turns BibTeX into \bibitem lines, and can look a reference up from its DOI or arXiv id:

const [entry] = await HaTeX.Bib.lookup('2006.11239');   // or a DOI, or an arxiv.org URL
HaTeX.Bib.format(entry);
// e.g. "\bibitem{ho2020denoising} J. Ho, A. Jain, P. Abbeel. Denoising Diffusion Probabilistic Models. arXiv:2006.11239, 2020."

See HaTeX.Bib for all the functions, and examples/editor.html for an "add reference" box built with them.

Footnotes

\footnote{text} puts a superscript number in the text and the note at the end of the document, in a numbered list. The number links to the note, and the note has a ↩ link back. Footnotes are numbered through the whole document. \footnote[5]{…} is accepted, but the number is ignored.

\footnotemark and \footnotetext are not supported.

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#Cross-references, citations and footnotes

#Labels

#References

#Clicking a reference

#Citations

#The bibliography

#Footnotes