[siliconfinance]

Thank you for your input and response.

If I understand correctly, would creating the following in a hook named 'prefix_choice_array_explode' work for my purposes?

if ($prefixchoice)
                {
                    $prefix_sql = array();
                    foreach (explode(',', $prefixchoice) AS $prefixid)
                    {
                        if ($prefixid == '-1')
                        {
                            // no prefix
                            $prefix_sql[] = "''";
                        }
                        else
                        {
                            $prefix_sql[] = "'" . $db->escape_string($prefixid) . "'";
                        }
                    }
                    $thread_query_logic[] = "thread.prefixid IN (" . implode(',', $prefix_sql) . ")";
                }

                ($hook = vBulletinHook::fetch_hook('prefix_choice_array_explode')) ? eval($hook) : false;