Multiple-link functions are functions that have arguments grouped in more than one pair of brackets. They appear in expressions of the type . Definitions of multiple-link functions enable the classification of arguments as either parameters or variables.
Example 1. The identity
defines a double-link function, where is a two-parameter family of linear functions.
Example 2. A formula for rotating the vector around the axis given by the unit vector through the angle is , involving dot and cross products of vectors.
Example 3. The identity
defines the definite integral of a function from to which avoids using the bound (or dummy) variable .