\setupinteraction[state=start]

\starttext

\setupfield[setup_1]
           [reset, horizontal]
           [option=printable, frame=off, bottomframe=on,
               width=4in, height=1.2em, offset=-1pt,
               frameoffset=2pt]
\definefield[line_1][line][setup_1][][]

This is an input line:    \field[line_1]

\blank

\setupfield[setup_2] [width=1.2em, height=1.2em, #1]
\definefield[check_2][check][setup_2][X,_][_]

Click this to see an “X” or check-mark:  \field[check_2]

\blank

\definefield[radio_3][radio][setup_3]
            [checkedButton,Aaa,Bbb,Ccc][checkedButton]
\setupfield[setup_3]
           [width=1.2em, height=1.2em, frame=off, background=screen]
\definesubfield[Aaa][][circle]
\definesubfield[Bbb][][circle]
\definesubfield[Ccc][][circle]

Aaa \field[Aaa]
Bbb \field[Bbb]
Ccc \field[Ccc]

\stoptext