In 1840 the jurist Friedrich Carl von Savigny named four elements of interpreting a law: “ein grammatisches, logisches, historisches und systematisches”, grammatical, logical, historical and systematic. German law students still learn them.
The systematic element reads a provision in the light of where it stands in the whole legal system. A Göttingen teaching script gives an example. A rule of the Trade Regulation Act stands in the title on established businesses. By general view, it therefore does not apply to traveling traders.