This is a proposal for a standard to be used for English abstracts and titles in scientific publication. The objective is to be easy to use (i.e. based on Latex rather than MathML) and unambigous.
The general format is simly
Text....$\latex$...Text...where Text is ASCII text with standard latex accents and escaping. \latex is ASCII code represnting a macro-free latex/amslatex representation of a text/equation. The following mathematical sybols/formatting commands are allowed:
\acute \agt \alef \alefsym \aleph \alpha \Alpha \alt \and \And \ang \angle \approx \arccos \arccot \arccsc \arcsec \arcsin \arctan \arg \atop \backslash \bar \Bbb \beta \Beta \beth \bf \big \Big \bigcap \bigcup \bigg \Bigg \bigodot \bigoplus \bigotimes \bigsqcup \biguplus \bigvee \bigwedge \binom \bmod \bold \boldsymbol \bot \Box \breve \bull \bullet \cal \cap \cdot \cdots \cfrac \check \chi \Chi \choose \circ \clubs \clubsuit \cnums \colon \complement \Complex \cong \coprod \cos \cosh \cot \coth \csc \cup \dagger \Dagger \daleth \darr \dArr \Darr \ddagger \ddot \ddots \deg \delta \Delta \det \Diamond \diamonds \diamondsuit \digamma \dim \dot \dots \dotsb \downarrow \Downarrow \downharpoonleft \downharpoonright \ell \emph \empty \emptyset \epsilon \Epsilon \equiv \eta \Eta \eth \exist \exists \exp \Finv \flat \forall \frac \frown \Game \gamma \Gamma \gcd \ge \geq \gets \gg \gimel \grave \gtrsim \hAar \harr \Harr \hat \hbar \hbox \hearts \heartsuit \hom \hookleftarrow \hookrightarrow \hslash \iff \iiiint \iiint \iint \Im \image \imath \implies \in \inf \infin \infty \injlim \int \iota \Iota \isin \it \kappa \Kappa \ker \lambda \Lambda \land \lang \langle \larr \lArr \Larr \lbrace \lbrack \lceil \ldots \le \left \leftarrow \Leftarrow \leftrightarrow \Leftrightarrow \leq \lesssim \lfloor \lg \lim \liminf \limsup \ll \ln \lnot \log \longleftarrow \Longleftarrow \Longleftrightarrow \longmapsto \longrightarrow \Longrightarrow \lor \lrarr \lrArr \Lrarr \lVert \mapsto \mathbb \mathbf \mathcal \mathfrak \mathit \mathop \mathrm \mathsf \max \mbox \mho \mid \min \mod \models \mp \mu \Mu \N \nabla \natnums \natural \ne \nearrow \neg \neq \ngeq \ni \nleftarrow \nleq \nless \nmid \not \notin \nrightarrow \nu \Nu \nwarrow \O \oint \omega \Omega \operatorname \oplus \or \otimes \over \overbrace \overleftarrow \overleftrightarrow \overline \overrightarrow \P \part \partial \perp \phi \Phi \pi \Pi \plusmn \pm \pmod \Pr \prime \prod \projlim \psi \Psi \qquad \quad \R \rang \rangle \rarr \rArr \Rarr \rbrace \rbrack \rceil \Re \real \reals \Reals \rfloor \rho \Rho \right \rightarrow \Rightarrow \rm \rVert \S \sdot \searrow \sec \sect \setminus \sgn \sharp \sigma \Sigma \sim \simeq \sin \sinh \smallfrown \smallsetminus \smallsmile \smile \spades \spadesuit \sqrt \square \star \sub \sube \subset \subseteq \subsetneq \sum \sup \supe \supset \supseteq \supsetneq \swarrow \tan \tanh \tau \Tau \textbf \textit \textrm \texttt \textvisiblespace \theta \Theta \thetasym \tilde \times \to \top \triangle \triangleleft \trianglelefteq \triangleright \trianglerighteq \uarr \uArr \Uarr \underbrace \underline \uparrow \Uparrow \updownarrow \Updownarrow \upharpoonleft \upharpoonright \upsilon \Upsilon \varepsilon \varinjlim \varkappa \varliminf \varlimsup \varnothing \varphi \varpi \varprojlim \varrho \varsigma \vartheta \vbox \vdash \vDash \Vdash \vdots \vec \vee \vert \Vert \wedge \weierp \widehat \wp \wr \xi \Xi \Z \zeta \ZetaCompare Wikimedia: this is essentially the set supported by texvc (used by Wikimedia), with the addition of approximately-less/greater-than symbols \lesssim (or \alt), \gtrsim (or \agt) and a few others (?) (see Texvc).
Citations
Citations should use defined macros \doicite (to site a DOI reference: e.g. "Following \doicite{Lewis and Challinor 2006}{10.1016/j.physrep.2006.03.002} we show...") or \repcite (to cite a repository reference such as an arxiv ID: e.g. "Following \repcite{Lewis and Challinor 2006}{arXiv:astro-ph/0601594} we show..."). [why don't arxiv papers have DOIs?] \cite may not be used.
As above for symbol set, but use WikiMedia format more directly, i.e.
UTF8TExt...<math>\latex</math> UTF8text...This would be more internationally-compatible, but probably harder to use. One advantage(?) is that it could also support Wiki-citation format.