Hi, Actually, the situation is going to be better from v2.23/12. Starting from this version all the ROOT object are taking advantage of the byte count facility. This means that any file produced by a release later than v2.23/12 will be readeable by v2.23/12, achieving forward compatibility (at last). Rutger is correct in pointing out that the addition of the StreamerInfo facility provokes Laurent's difficulty. However this should be a problem ONLY for the TNtuple, the TTree should not be affected by this problem (this is because the StreamerInfo is append to the TTree::streamer which is __contained__ inside the TNtuple streamer). So if you do need file created by v2.23/12 or above readable by older root, stick with straight TTrees. Cheers, Philippe -----Original Message----- From: owner-roottalk@pcroot.cern.ch [mailto:owner-roottalk@pcroot.cern.ch]On Behalf Of Rutger van der Eijk Sent: Thursday, March 09, 2000 6:36 AM To: ROOT mailing list Subject: Pb. of backward compatibility ? Hi Laurent, The thing you want is forward compatibility, i.e. read with a older version the output of a newer version. This is almost never the case for software. I expect the in v2.23/12 added 'StreamerInfo facility' to cause the problems => i.e. the format of the files changed => no forward compatibilty. You therefore have to move all your platforms/users to latest version (or forget about newest) Cheers, Rutger
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