Am 09.09.2014 um 18:44 schrieb seasoul <bioseasoul@gmail.com>:

> Is there an already-exsting or easy way to add annotations to equations, just something like 
> 
> annotation1.png

You can use the \underbrace and \overbrace commands.

\starttext

\startformula
\underbrace{f(n)}_{\text{Output}} = \underbrace{\overbrace{n}^{\text{Input}} + 3}_{\text{Rule for Function}}
\stopformula

\stoptext

Wolfgang