“…Some are now considered optional, rather than essential, such that threshold concepts may now be described as probably irreversible, having the capacity to be integrative, being possibly bounded, or as potentially troublesome (Barradell, 2013;Carmichael, 2012;Meyer & Land 2006a;Rowbottom, 2007); there does, however, appear to be fairly wide agreement that being transformative is an essential property of a threshold concept Carmichael, 2014;Meyer & Land, 2006a;Quinlan et al, 2013;Rowbottom, 2007). It has also been proposed that threshold conceptions (Land et al 2005), threshold capabilities , threshold skills (Thomas et al, 2014) or threshold experiences (Foley, 2014), rather than threshold concepts, might be more useful constructions.…”