Does this notation have a special meaning? I am currently reading a paper and I don't know how to interpret this notation you can see on the screenshot.

http://moxn.brainex.de/pub/dfg.png

Do the pointy angle brackets have a special meaning or did the author choose them just to confuse me?

I googled it and apparently they are commonly used in group theory, which does not make much sense to me here.

Thanks for your input.

btw: The paper is called "A Formal Definition of Data Flow Graph Models" by Kavi, Buckles and Bhat, and is available here.
No special meaning here. The angle brackets simply denote a tuple or pair. The author chose the angle brackets to look prettier than the usual round parentheses. Thus a graph $G$ is a set of vertices $A \cup L$ and a set of edges $E$.