Grouping Dimension

[Ronald]

I´ve created dimension and show QTR0 and QTR-1:

=if(match(Mes,'M60','M59','M58'),'QTR0',
if(match(Mes,'M59','M58','M57'),'QTR0-1'
))

the sum of QTR0 is correct, but QTR-1 don´t sum M59 and M58, because is in QTR0.