I believe there is some good paper out there on http://www.lexjansen.com/sugi/ about this, but when I was preparing myself for base cert. I read this SET, MERGE , UPDATE, SUM (I think there are couple of more ) act as Retain because of the way the data step processing works.Why ........... Look out for key word on PDV (program data vector )

thanks

On 10/3/06, avi <aviben@bezeqint.net.il> wrote: > > Hello, > > Though an quite experienced user of SAS, i was quite surprised to learn > that in some cases, observations retain their values from one obs to > another, without specifying the RETAIN statement > ("When variables are read with a SET, MERGE, or UPDATE , The variables > retain their values until new values become available"). > > Could someone explain exactly what and why it happens and the way to > overcome the problem thaht has caused some disturbing results in one of > my applications? > > > Thaks a lot > Avi >