When talking about quantum parallelism, in Nielsen and Chuang, it's said that:
it is possible to transform this state into $|x, y \oplus f(x)\rangle$, where $\oplus$ indicates addition modulo 2; the first register is called the ‘data’ register, and the second register the ‘target’ register.
I'm confused about why the first register is called the ‘data’ register and not the ‘control’ register. Is there a difference between a data register and a control register? Is ‘data’ register a standard name in EE or just in QC?