> Pablo Rodriguez <mailto:oinos@gmx.es>
> 26. Januar 2016 um 09:42
>
> Many thanks for your reply again, Ibn.
>
> I’m afraid this is something different of what I intend to ask here (in
> fact, I use \setupinteraction in my docments too).
>
> I guess \definehead is what I should be using.
No, the makeup environment is the right mechanism. You can combine this
with the \setvariables command and create the title page when you set 
the values.

\definemakeup[titlepage][align=middle]

\startsetups[titlepage]
     \startmakeup[titlepage]
         \startfont[SansBold sa 3]
             \getvariable{titlepage}{title}
         \stopfont
     \stopmakeup
\stopsetups

\setvariable{titlepage}{set}{\texsetup{titlepage}}

\starttext

\setvariables[titlepage][title=Titlepages for dummies]

\stoptext

Wolfgang