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1.4.4.13 The ``Method Signature'' Section of a Dictionary Entry

The description of a *generic function* includes descriptions of the *methods* that are defined on that *generic function* by the standard. A method signature is used to describe the *parameters* and *parameter specializers* for each *method*. *Methods* defined for the *generic function* must be of the form described by the *method* *signature*.

**F** *(**x* *class*) (*y* t) `&optional` *z* `&key` *k*

This *signature* indicates that this method on the *generic function* **F** has two *required parameters*: *x*, which must be a *generalized instance* of the *class* *class*; and *y*, which can be any *object* (i.e., a *generalized instance* of the *class* **t**). In addition, there is an *optional parameter* *z* and a *keyword parameter* *k*. This *signature* also indicates that this method on `F` is a *primary method* and has no *qualifiers*.

For each *parameter*, the *argument* supplied must be in the intersection of the *type* specified in the description of the corresponding *generic function* and the *type* given in the *signature* of some *method* (including not only those *methods* defined in this specification, but also *implementation-defined* or user-defined *methods* in situations where the definition of such *methods* is permitted).

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