Thank you for answering, Jonathan.
I've used ACS 3.4 (the new DB API are available from this release, I think). I also followed the reccomendations of Philip Greenspun published in 'Building documents in ACS' using ad_page_contract, doc_set_property and doc_body_append.
I have to establish programming standards for a new project and so I need to know if there are relevant API differences between ACS 3.4 and OpenACS. Ideally I would build an application capable of working both with Oracle and PostgreSql.
Claudio Pasolini