On 2013–08–26 "H. Özoguz" wrote:

> >The following text has protrusion and is justified.
> >
> >\setuplayout [width=6cm]
> >\definefontfeature [default] [default] [protrusion=pure]
> >\setupalign [hanging]
> >\showframe
> >\starttext
> >   \spaceskip=1ex plus 1ex minus .2ex
> >   \input knuth
> >\stoptext
> >
> >>/  forcing a constant distance.
> >/
> >If you provide stretch and shrink the distance is not constant.
> Thank you! I dont understand this command, what does "1ex plus 1ex
> minus .2ex " excactly mean?

It's the inter-word glue, which is usually a property of the font
and is usually not altered by the user. However, \spaceskip is used
for e.g. ragged text and special alignments.

Read up about glue in your favourite TeX reference. \spaceskip is
covered in TeX by Topic¹, chapter 20. The first value is the
“natural” size. If necessary it can stretch or shrink by the given
amount which can be zero.

> I am asking for the example :)

You said it doesn't justify after I sent you a minimal example which
was justified. That's what I was talking about.

Marco

¹ http://www.eijkhout.net/texbytopic/texbytopic.html