With this example code from the wiki (slightly modified for use here):

\setuppapersize[A5]
\starttext
\placeformula[eq:pythagoras]
\startformula
  a^2+b^2=c^2
\stopformula
This is explained in \in{Equation}{.}[eq:pythagoras]
\stoptext

The following output is obtained:

A good excuse to stop for the night, thank you.

--
Rik