Supported TeX

The representative commands below are evidence-backed, not an exhaustive grammar. The symbol and command tables are broader than these examples.

Core Math

Supported and tested:

letters, digits, Unicode math characters, control symbols, and named symbols;
automatic atom classes and relation/binary/operator spacing;
superscripts, subscripts, primes, and simultaneous scripts;
\frac, \dfrac, \tfrac, binomials, supported \genfrac forms, and barless/infix fraction forms represented by the neutral IR;
\sqrt and indexed roots;
named operators such as \sin, \lim, \det, and \operatorname;
\limits and \nolimits when attached to a valid operator;
math alphabet commands such as \mathrm, \mathit, \mathbf, \mathbb, \mathcal, \mathfrak, \mathsf, and \mathtt;
math class commands such as \mathrel, \mathbin, and \mathop;
explicit spacing, \allowbreak, and basic \not negation.

Examples exercised by the daily corpus include quadratic formulas, sums, products, integrals, limits, derivatives, Maxwell equations, the Schrodinger equation, probability expressions, sets, and piecewise cases.

Delimiters and Fences

Supported and tested:

literal delimiters and named forms such as \lfloor, \rfloor, \langle, \rangle, \vert, and \Vert;
\left...\right, including \middle;
TeX size commands such as \Bigl...\Bigr;
paired and one-sided fences, null delimiters, and fence hits;
matrices with matrix, pmatrix, bmatrix, Bmatrix, vmatrix, and Vmatrix, including starred variants;
cases, dcases, rcases, and drcases;
array, darray, and subarray with l, c, and r column specifications and supported rule syntax;
aligned, gathered, split, alignedat, alignat, align, gather, equation, and their tested starred forms where implemented.

Unmatched fences, unknown environments, mismatched \begin/\end, and invalid column specifications report diagnostics and recover.

Decorations and Boxes

Supported and tested:

\overline, \underline, and \underbar;
braces, brackets, groups, under/over arrows, and common extensible arrows;
\overset, \stackrel, and \underset;
common accents such as \hat, \tilde, \bar, \vec, \dot, \ddot, and combining accents accepted by the text frontend;
\cancel, \bcancel, \xcancel, and \sout;
\boxed, \fbox, \colorbox, and \fcolorbox;
\phantom, \hphantom, \vphantom, \smash, and \mathstrut;
\rule and supported explicit dimension units.

Text, Color, Links, and Styling

Supported and tested:

\text, \textrm, \textnormal, \textsf, \texttt, \textbf, \textmd, \textit, \textup, \textsl, \emph, \mbox, and \hbox;
common text symbols and text accents;
named colors and supported #rrggbb color syntax;
declarative \displaystyle, \textstyle, \scriptstyle, and \scriptscriptstyle;
declarative alphabet switches such as \rm, \it, \bf, \sf, \tt, and \cal;
\char and \verb where their argument form is supported;
visible link bodies for \href and \url.

Links are deliberately text-only. The destination is discarded and the parser emits an unsupported warning after the arguments validate. Labels, references, and document-level link resolution are outside the API.

Macros

The TeX frontend supports:

host macros through ParseOptions.Macros;
\def, \gdef, \edef, and \xdef;
\newcommand, \renewcommand, and \providecommand;
scoped expansion with argument placeholders and macro origin tracking.

This is a bounded formula macro expander. It is not a general package or document execution engine.

Equation Tags

Phase 1 supports top-level TeX display tags:

\tag{...} renders parenthesized tag text;
\tag*{...} renders without automatic parentheses;
\nonumber and \notag produce suppression metadata.

The following are explicitly outside the current tag contract and produce diagnostics rather than being promoted silently:

tags in inline math;
tags inside a nested group;
tags inside a supported environment;
more than one manual formula-level tag;
promotion of a tag from a script, fraction argument, root index, or similar syntactic argument;
automatic document counters and references.

Constrained tagged display output intentionally does not wrap to multiple lines. See Rendering the display list for the tag-box drawing contract.

Explicit Exclusions

The following capabilities are not treated as silently ignorable TeX:

Input family	Current behavior
Chemistry and units: `\ce`, `\pu`	Error diagnostic; visible unsupported placeholder.
External images: `\includegraphics`	Error diagnostic; visible unsupported placeholder.
Raw HTML/DOM hooks: `\htmlClass`, `\htmlData`, `\htmlId`, `\htmlStyle`	Unsupported or discarded metadata with diagnostics; no DOM.
Commutative diagrams: `CD` environment	Unsupported diagnostic; bounded environment skip.
Manual overlap/raise/centering: `\llap`, `\rlap`, `\clap`, `\mathclap`, `\raisebox`, `\vcenter`, `\phase`	Unsupported; neutral IR cannot represent the geometry losslessly.
KaTeX size declarations: `\tiny`, `\small`, `\large`, and peers	Unsupported because the neutral IR does not expose a KaTeX size index.
`\nobreak`	Unsupported because suppression-only break policy is not represented.
Inline math delimiters nested in math mode: `\(`, `\)`, `\]`	Parse diagnostic.
Math commands in text mode, such as `\sqrt` inside `\text`	`unsupported` diagnostic at the text-mode boundary.
Document packages, counters, references, citations, file inclusion, and arbitrary conditionals	Outside the formula frontend.

Recovery Is Part of the Contract

Common malformed inputs are tested:

\frac{1} -> missing-argument, recoverable;
\left(x -> unclosed-group diagnostics, recoverable;
unknown environments -> invalid-environment, recoverable;
repeated/conflicting infix operators -> unexpected-token;
undefined control sequences -> unknown-command;
excess input or parser work -> limit-exceeded.

The preview remains drawable unless layout fails for a separate reason.

What "Supported" Means

For this project, "supported TeX" means:

the syntax lowers to canonical IR;
canonical IR validates;
layout is tested to produce a valid box or an explicitly expected layout error;
tracked conformance and daily corpora classify the result;
any known gap is recorded in a policy or baseline instead of being hidden.

It does not mean every command accepted by KaTeX, every LaTeX package, or every visual edge case of TeX is implemented.