Everything that doesn't require aiders and can't be honestly called 'free climbing'. Placements are easy and bomber. Each piece should hold a fall. Solid but often awkward and strenuous placements. Maybe a difficult placement or two above good pro.
Falls pose no danger.
Moderate aid, but with more tenuous placements above good pro. There is a potential for serious falls, but these will generally be otherwise uneventfull. Requires many tenuous placements in a row and pieces need to be tested before weighting them. There should be solid placements within the pitch, but they are rather few and far between. During a fall, up to eight pieces of pro may rip out, but there generally is little serious danger.