Hi, There seems to be a problem with the structure information added when using \startmatrix: \setuptagging[state=start] \starttext \math{ \startmatrix \NC A \NR \NC B \NR \stopmatrix} \stoptext The log reports an open chain: document>1 => mtr>1 => mtd>1 => mtr>2 => mtd>2 => mtr>3 This may be a bug. Kind regards, Christoph