I'd describe parent as a control flow graph, not a data flow graph. Control flow makes clear the interpretation of that cycle as an iterative "loop". In data

I'd describe parent as a control flow graph, not a data flow graph. Control flow makes clear the interpretation of that cycle as an iterative "loop". In data flow, the cycle shown in your parent comment would instead represent an arbitrary fixpoint: the output of 'end' would be some value x = end(loop_body(init(x))). This inherent ambiguity where the same constructs are given different semantics is actually one reason why visual representations can sometimes be confusing. The same applies to parallelism - does it represent divergent choice, or a fork/join structure where independent computations can be active at the same time? You can't make both choices simultaneously within the same portion of a diagram! Of course you could have well-defined "sub-diagrams" where a different interpretation is chosen, but since the only shared semantics between the 'data flow' and 'control flow' cases is simple pipelining that's so limited that it isn't even meaningfully described as "visual", it's hard to see the case for that.