Math & Science ⇒ xalignat, xxalignat, subequations and flalign environments

[johnnycc]

I am using a tool to convert LaTeX math into MathML. The tool does not support environments like xalignat, xxalignat, subequations and flalign but it supports align and alignat. I am not looking for the accurate rendering of the formula. Thus I thought I could replace the name of the environment, e. g. replacing xalignat with alignat.

Code: Select all

\begin{xalignat}{3}
i_{11} & =0.25 & i_{12} & =i_{21} & i_{13} & =i_{23}\nonumber\\
i_{21} & =\frac{1}{3}i_{11} & i_{22} & =0.5i_{12}& i_{23} & =i_{31}\\
i_{31} & =0.33i_{22}\quad & i_{32} & =0.15i_{32}\quad & i_{33} & =i_{11}
\end{xalignat}

\begin{alignat}{3}
i_{11} & =0.25 & i_{12} & =i_{21} & i_{13} & =i_{23}\nonumber\\
i_{21} & =\frac{1}{3}i_{11} & i_{22} & =0.5i_{12}& i_{23} & =i_{31}\\
i_{31} & =0.33i_{22}\quad & i_{32} & =0.15i_{32}\quad & i_{33} & =i_{11}
\end{alignat}

I have done some tests and I am satisfied with the results. I have replaced
xalignat with alignat,
xalignat* with alignat*,
xxalignat with alignat*,
flalign wih align and
flalign* wih align*align*.

I couldn't find any replacement for subequations.
My question is would the replacement work for every possible content? E. g. is there a structure for flalign environment that would cause an error in align environment?