Hello all!

I'm interested in change the natural numbering of one equation with \eqno{}
but it does not follow the main font selected.

A minimal example:

%%%%%%%%%%%%%%%%%%%%%%
\usemodule[simplefonts]
\setmainfont[Linux Biolinum O]
\setmathfont[Linux Biolinum O]

\starttext

I have the following expression

\placeformula
\startformula
y = Z \beta_1 + Y \beta_2 + u
\stopformula

that changes to

% \placeformula
\startformula
y = Z \beta_1 + Y \beta_2 + W_1\tau + u \eqno{ (1')}
\stopformula

\stoptext
​%%%%%%%%%%%%%%%%%%%%%%​

​I would like the (1') ​keep the same kind of font than (1).

Any hint will be appreciated.

Thanks!

-- 
«...my role is to be on the bottom of things.»

Donald Knuth