Certain Biblical paragraphs are stated in a Theme-Development form. In other words a broad general idea is stated first followed by the development of this broad general theme in specific details. The Theme-Detail form creates a unified paragraph and consequently the law only applies to the enumerated details but not to other cases. Today's example illustrates this as shown below.

Verse Nu03-06a is written in a General-Detail form: Bring the tribe of Levi near, and set them before Aaron the priest, that they may minister unto him. Notice the word that which indicates the transition in the general-detail form. The Rabbi Ishmael style rules require that such a sentence be interpreted restrictively. Levites help the priests only by serving and ministering to them (e.g. by singing songs of praise during the Temple service); but not e.g. by offering sacrifices. Rashi derives this restrictive interpretation from the Detail clause - that they may minister unto him - which restricts the general clause Bring the tribe of Levi near and set them before Aaron the priest. Without this restrictive clause I would have interpreted the verse to mean that the Levites generally help the priests in all matters including offerings.