<context source="yes">
\setuppapersize[A5]
\setupdelimitedtext
[quotation]
\definestartstop[extract][
before={\blank[extractdistance] %[extractdistance,force] causes spurious % overfull \hbox warnings
\setupnarrower[left=1.5pc,right=1.5pc]
\startnarrower[left,right]