Reference of particular value in a group outside the group

My ecel file look lig

begin_group CMR
text observation
end_group CMR

I try to acces outside the value of the fiel observation in a calculation filed by


none works.

what could be the correct syntax ?

EDIT: deleting my post because I misread and though @Fabienne35 was asking about a repeat group

@Fabienne35 the correct syntax is ${observation}. you can directly reference a question if it is inside a begin group