This is necessary because otherwise, newly created items based on default values might point to the wrong user, if default values are not cached per user.
It is now possible to say .../sale.order?state=draft&state=done to get a list of all orders with (state in ('draft', 'done')).
Every XML element in the <content> gets a prefix that corresponds to its type, e.g., "rpa" for "res.partner.address". This helps us 1. to avoid problems with multiple no-prefix namespaces and 2. allows to mix XML from different object types together.
this is needed for, e.g., delivery.sale.order
pass [(6, 0, ids)] instead of just ids to XML-RPC call; didn't test whether it also works with one2many