In the book Happiness at work by S. Rao there is mention of regulation headgear:
April glanced out from the upstairs bedroom window. There were two men on the stoop outside. She could not see their faces because they wore regulation headgear. Both were in uniform.
These are army men, who came to a woman to tell April that her husband has been killed in action.
I assume that regulation headgear means some sort of army hats or caps. I thought they may look like this:
But it's wrong - according to the paragraph, the headgear obscures the face.
Then I thought that maybe it something like this:
It obscures the face alright, but there is a problem. I assume that in the paragraph above the story takes place in some peaceful region. It's hard to imagine that people, even army people, walk around in helmets like these. I don't see the purpose.
Therefore my question: What kind of headgear is likely to be meant by regulation headgear in the paragraph above?