In fact you should say \NR[+] at the end of each line in \startalign in order to get numbers. This works for me: \starttext

\placeformula \startformula \startalign \NC \dot{x}(t) \NC=f(x(t), u(t)) \NR[+] \NC y(t) \NC=h(x(t), u(t)), \NR[+] \stopalign \stopformula

\stoptext

Wow, that's pure magic! Thanks! ) -- Best Regards, Vyatcheslav Yatskovsky