waiting - is a child of 'exposure of material to environment', has a negative definition = not actively doing anything to a material for a duration of time.
which is inconsistent with the parent class 'exposure of material to environment' it's too generic- suggest delete this, or reformulate definition and move up one level. New definition: waiting: is a process in which no activity occurs for some period of time - I admit this is not much better as a def. There's a comment BP: I doubt the utility of this. I agree.
Discussed on 2016-10-24 OBI call. We agreed with the comments on the term 'waiting'. It needs further discussion. When we find better term(s), we should obsolete 'waiting'.