With a little additional work; here is how I can control to present all of them or just some based on a limit parameter: For reference; this is within the foreach of an array of zones being passed - you can see this in most of the delivery files (e.g. ax.php: line 4307)
if ( $limit === 0 ){
$allAds = MAX_cacheGetZoneLinkedAdInfos ($thisZoneid);
$aBannerIds = array_keys($allAds['xAds']);
foreach( $aBannerIds as $adId){
$what = "zone:".$thisZoneid.",+bannerid:".$adId;
$aBanners[] = MAX_adSelect($what, $campaignid, $target, $source, $withtext, $charset, $context, true, $ct0, $loc, $referer);
}
} else {
$what = "zone:".$thisZoneid;
do {
$aBanners[] = MAX_adSelect($what, $campaignid, $target, $source, $withtext, $charset, $context, true, $ct0, $loc, $referer);
} while(--$limit > 0);
}