3.1 and higher uses Edismax, lower is dismax.
[13-02-07 3:34:33 PM] Jordan Dukart: edismax was added in as in option in using solr_search
[13-02-07 3:34:37 PM] Jordan Dukart: in 7.
[13-02-07 3:34:52 PM] Jordan Dukart: http://wiki.apache.org/solr/ExtendedDisMax
if you want to use it in development it's just changing the type in the url.