Would be much better to store default prefixes in $GLOBALS in constants.php, otherwise we have to declare global $default_prefixes before including RdfAPI.php in order for SPARQL parser to see it (see http://php.mirror.camelnetwork.com/manual/en/migration4.variables.php\).
Not a big deal of course, only that I just spent a couple of hours trying to work out why this wasn't working :D
Logged In: YES
user_id=1796871
Originator: YES
Same for global $sparql_describe etc.