sclp_vt220_space_left
if (count > sclp_vt220_space_left(request))
count = sclp_vt220_space_left(request);
(from < count) && (to < sclp_vt220_space_left(request));
if (to + 1 < sclp_vt220_space_left(request)) {
count = sclp_vt220_space_left(sclp_vt220_current_request);