Thanks Sergiy, in the end I choose a semicolon-delimited string containing the dose number without spaces in order to explicit all the dose for that group.
Using the new engine 2405.2, I found a new warning in dataset validation on the value of TXVAL when TXPARMCD = ‘TRTDOS’. In this case, I have a dose expressed as a character because it is a concatenation of two doses, because the subject took two different doses of the treatment. Is there a way to manage this warning or have I to only justify that on nsdrg?