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#### 11.1.2 Implementation Packages

Each package has a list of associated implementation packages. A locked package, and the symbols whose home package it is, can be modified without violating package locks only when `*package*` is bound to one of the implementation packages of the locked package.

Unless explicitly altered by `defpackage`, `sb-ext:add-implementation-package`, or `sb-ext:remove-implementation-package` each package is its own (only) implementation package.