[NTG-context] Different width of marginblocks and margindata

Hi, in the following example, why do marginblocks and margindata produce a different width when both are set to the same value? \setupmarginblocks [width=\rightmarginwidth] \setupmargindata [inright] [style=normal, width=\rightmarginwidth] \showframe \starttext \startmarginblock Text in paragraph. \stopmarginblock \input knuth \inright{Text in paragraph.} \input knuth \stoptext Marco