I am searching for the name of an arrangement typically used in news-broadcast designs, exemplified below (Terror in Boston, with rectangle above). In French we call these mortaise, but I cannot find the English term for it.
Although a naming convention for Television News Graphical Layout might exist, the names for those kind of graphical elements may vary from place to place in the world depending on how a certain culture/business field prefer to reference/call those. Anyway, the one in the image you provided I believed it's called "Over the Shoulder", see this paper for more details.
The graphic element "Over the Shoulder", normally appears in the news that has higher impact, therefore revealing the relevance of the news story. The term "Over the Shoulders" is applied because it generally appears in the superior part of the shoulder of the anchor. The "Over the Shoulders" is usually accompanied with an image or icon, with the intention of establishing a link with the news story being presented.
Many of these elements are sold as ready made video packs, most of the time as editable After Effects projects on marketplaces such as videohive.net which usually include elements such as Openers, Bugs, Lower Thirds, Split Screens, Text Tickers, Over the Shoulders, Info Screens, Bumpers, and many others.
I hope it helps.
As a professional video editor working in broadcast, and as a college-educated broadcast journalist, this graphic is indeed called an "over-the-shoulder" (or OTS, for short).