[NTG-context] Multicolumn enumeration in a column

Hello, How to modify the code for an enumeration on three columns in a column ? Thank you Fabrice \definemixedcolumns [Mycolumns] [ n=2, separator=rule, rulecolor=, balance=, grid=strut, ] \setupalign[verytolerant,stretch,hanging] \setuppapersize[A4,landscape] \setupinteractionscreen[option=landscape] \starttext \startMycolumns \startitemize[n] \item \item \blank \startitemize[a,columns,three,joinedup] \item \item \item \stopitemize \stopitemize \stopMycolumns \stoptext