I'd define long scale to mean that a greater subject brightness range can be recorded by film A compared to film B, a short-scale film. A comparison could be TMX 100 vs Tech Pan.(posted 8074 days ago)TMX can record an SBR of at least 15 stops (that's as far as I measure) with a fairly straight-line response or iow the density increase stays proportionate to the exposure increase. There's no shouldering of any significance within this range. Although the DR may be unprintable in a straight print, if you burn highlights you can still print highlight detail/contrast.
TP otoh can record only about seven stops before abruptly shouldering to D-max. More exposure doesn't result in any more density, therefore there's no highlight detail/contrast and no highlight detail can be printed by burning in. It'll just make a very light detailless grey a darker detailless grey.
So I consider TMX to be a long-scale film and TP to be a short-scale film.
IMHO the ideal film has a rather broad shoulder rather than a straight line or a abrupt shoulder; this would allow a subject with a higher SBR to be recorded and printed in a straight print but would still have sufficient highlight contrast that highlight detail would be visible.
A couple of examples of this are Delta 3200 and Delta 400.