Board Thread:Questions and Answers/@comment-394774-20150224185718/@comment-394774-20150319161107

Any other evidence pop up either way?

I think strong arguments can be made both ways, but if we were to go purely on on-screen evidence, Winter Soldier's use of mixed-case is the only one that comes to mind, which would mean mixed-case is correct. (Although it's entirely possible there are other on-screen displays I've missed, especially in AoS, and I'd certainly like to know what those indicate if there are any.)

Stretching beyond that to quasi-canonical sources like the subtitles and storybooks, I would say the frequency of all upper-case would lean toward that being correct, even if it's a roughly 50/50 split*, since it's far more likely someone would unintentionally type it in mixed-case (or an auto-correct would change it to such) than it is that they would unintentionally type just that word in all upper.

I'm still mystified as to why it would be all upper, but that's neither here nor there.


 * Note: I'm not claiming it's 50/50; I haven't counted to see. I'm just making a point that all other things being equal the weight for all upper seems inherently stronger, even if I'm not a fan of it.