SH_SUBSCRIBER
sub = SH_SUBSCRIBER(shp, i);
SH_SUBSCRIBER(shp, i) = NULL;
if (SH_SUBSCRIBER(shp, sub_id) != NULL) {
SH_SUBSCRIBER(shp, sub_id) = sub;
sub = SH_SUBSCRIBER(shp, sub_id);
SH_SUBSCRIBER(shp, sub_id) = NULL;
if (SH_SUBSCRIBER(shp, sub_id) == NULL) {
sub = SH_SUBSCRIBER(shp, i);
sub = SH_SUBSCRIBER(shp, i);
SH_SUBSCRIBER(shp, i) = NULL;