Jason,
$url = 'http://boss.yahooapis.com/ysearch/web/v1/'.urlencode($term).'?appid='.$appID.'&view=keyterms&sites='.urlencode($sites).'&abstract=long&count='.$count.'&format=xml&start='.$start;
I also used this thread on this forum as a reference showthread.php?t=13558 but again, not being a programmer, I undoubtedly misuse some reference material.
Dennis