whats is the difference between merge and join .
Sigiloso
Using join you can split lines (duplicate). For example, you have AETERM in Adverse Event, where AETERM = "headtoothache". It's 2 independent DECOD, and if you need to control it by MedDRA dictionary you need to split lines where AETERM in both lines equal to 'headtoothache' but AEDECOD in the first line equal to 'HEADACHE' and 'TOOTHACHE' in the second line.