savepoint and rollback

I hope someone can help me out with this (simple??) problem. I generate large sql files that are based on datasets. This data will be place din different tables. Part of the sql files is the creation of temporary tables which hold the links between the tables in Oracle. Since I'm still in the design and testing stage there maybe some errors in the sql files and I want to be able to rollback to the initial state of the database, before I gave the command: 'start load_data'. I gave a 'savepoint goback' command but after the job was completed and I tried to give 'rollback to savepoint goback' I got the message 'savepoints specified' or something similar. How come?? So my questions are:
1] How many sql statements are possible within a savepoint/rollback sequence.
2] How do I get this thing working?
3] I remember that a create table gives an automatic commit and after a commit all the previous savepoints are undefined, is this true??

Thanks
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        Paul Sjoerdsma, Godwin Laboratory, Free School Lane,
                     Cambridge CB2 3RS England
       fax:   (44) (0)223-334871, email: pgs1002_at_cus.cam.ac.uk


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