On 2013–09–06 "H. Özoguz" wrote:

> I want to set before all question marks of a large document one
> "\narrownobreakspace".

Set up the character spacing for the question mark. No changes to
the markup required.

\definecharacterspacing
  [MySpacing]

\setupcharacterspacing
  [MySpacing]
  [\number`?]
  [left=.2]

\setcharacterspacing
  [MySpacing]

\starttext
  What? And why?
\stoptext

Marco