Caption label formatting in Context

Question

I am trying to introduce a linebreak after the caption label so that the caption starts below the caption label in context. However, the suffix key for the \captionsetup only accepts text like : or --. I would like something like this:

MWE:

\setupbodyfont[modern,11pt]
\setuplayout
  [width=11cm,
   rightmargin=6cm]

\setupcaption
  [figure]
  [width=\rightmarginwidth,
   headstyle=smallcaps,
   suffix={:},
   prefix=yes,
   way=bysection,
   prefixsegments=chapter,
   align=right,
   location={rightmargin,high}]

\starttext
\showframe
\chapter{One}
\placefigure{A cow is a cow is a cow.}{\externalfigure[cow]}
\stoptext

Answer 1

\setupcaption
  [figure]
  [distance=\textwidth]

The distance key specifies the space between the suffix and the actual caption text. I actually looked into the source to find out the possible options. The manual and wiki are both helpful and mostly provide detailed explanations, but are often incomplete. The sources are – by definition – complete and up-to-date.

In strc-flt.mkvi you find that the default value for distance is 1em:

\setupcaptions
  […
   \c!distance=1em,
   …]

Further down this value is assigned to \scratchskip. Now you know that distance is a glue value with the default size of 1em and no stretch or shrink which is being inserted between the suffix and the caption text. If this value is increased beyond the size of the surrounding box (the actual value does not matter) ConTeXt places the content on the next line.