I have read it throughly, it clarified. Still not mastering when old and new api are mixed.

The old api and the new api differs in the use of the arguments cr. uid, ids, context, in the return of the methods. When the new api manage recordsets, in the old api you manage everything. Think the new api as using Active Records while the old api you call the methods to get the values even when the browse_record class acts a little as an Active Record in the old api. The browse in the new api and the old api only differs in that for the new api the arguments cr, uid and context are not needed since they are retrieved from the Environment attached to self