There is an incorrect definition in Manual’s Grid Applications > Grid > Group By > Events page. It says use _breaking for ?calculate during the breakings? but it doesn’t work. If you use _groupby instead of _breaking it works.
[INDENT]For example:
{sum_breaking_parcel} defination doesn’t work.
{sum_groupby_parcel} defination works.[/INDENT]
I think the manual translation is wrong.