That's an excellent question.
Operational stress injuries is the term that has been defined by the Canadian Forces and Veterans Affairs. I think the important piece is that it shows that post-traumatic stress is not the only disorder that can happen related to combat stress or trauma. It is a signature condition but generalized anxiety disorder, panic disorder, and other conditions can also be linked.
The other thing that's important for you to know is that there's a move in psychiatry away from dichotomous “does the person meet the full criteria for a condition or not?” Lots of people who come with some threshold PTSD symptoms are resilient. They have lots of supports but they're struggling with nightmares or having difficulty with irritability, and it's linked to their service. The Canadian Psychiatric Association agrees with this terminology.
The other question is occupational stress versus operational stress, I think that is a bit of semantics because there's a whole literature on occupational health, and I think the aim is to try to link the mental health difficulties to the occupation. I'll try to make some comments around this at another opportunity. The most emotional difficulties are an interplay between the stressor and pre- and post-vulnerability. When I'm sitting with a person it's hard to try to figure out if it's exactly related to their work or not, and we've done work showing that it's a combination. Adverse health experiences—family stress, financial stress—impact on and worsen symptoms as well as a person's recovery.