In reply to john arran:
> Only in English has 'slab' been appropriated by climbers to have a specific low-angle meaning.
Been thinking about this. I'm not sure that, in the climbing sense, "slab" or at least "slab climbing" is simply a function of angle. To me "slab climbing" means predominantly depending on pure friction for the feet with the hands only used for balance. Something at the same angle which depends on standing on and pulling on small edges is not really, to me, slab climbing; it is probably better described as "off vertical" climbing. So I would argue that most off vertical slate climbing is not "slab climbing" (even though it might take place on a "slab"). Slab climbing is really just a subset of off-vertical climbing.
Anyway watched the film - I'm not sure it gave a very good impression of what the climbing is actually like (apart, obviously, from being desperate).