[NTG-context] Multiline text in mathmode

[Aditya Mahajan]

On Thu, 30 Jun 2022, Johann Birnick via ntg-context wrote:

> I guess you will update to LMTX..? Unfortunately I use MkIV, because of other
> math bugs in LMTX. Do you know any (can be ugly) way of doing this without the
> new stuff?

You could just use a framed. 

\define[1]\multilinetext{\vcenter{\framed[align=middle,frame=off]{#1}}}

\startTEXpage[offset=2mm]
  \startformula
    \left\{ \multilinetext{Quaternion algebra over $\rationals$ \\ up to
    isomorphisms} \right\}
  \stopformula
\stopTEXpage

Aditya