A more thorough explanation:

Definition: A signal is a word or phrase that briefly indicates the relevance of one or more cited sources. In formal legal writing, a signal often appears at the start of a citation sentence. The signal helps the reader understand the relationship between the cited source and the argument being made.

• "According to Smith, [signal] the plaintiff's argument is flawed."
• "[Signal] In contrast to the plaintiff's position, Jones argues that..."

In the first example, the signal "according to" indicates that the following citation from Smith's work supports the argument that the plaintiff's argument is flawed. In the second example, the signal "in contrast to" indicates that the following citation from Jones's work presents an opposing argument to the plaintiff's position.