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+# Custom attributes
+
+The `Copy` and `Clone` traits support the following attributes:
+
+* **Container attributes**
+    * [`<Copy or Clone>(bound="<where-clause or empty>")`](#custom-bound)
+    * [`Clone(clone_from="true")`](#clone-from)
+* **Field attributes**
+    * [`<Copy or Clone>(bound="<where-clause or empty>")`](#custom-bound)
+
+# `clone_from`
+
+The [`Clone`] trait has a default implementation for [`clone_from`] and
+`derive(Clone)` never implements that method. *derivative* can implement it if
+asked explicitly.
+
+Note that while the generated implementation is good for structures, it might
+not be very efficient for enumerations. What it does is check if both `self`
+and the clone-from value have the same variant, if they have, use `clone_from`
+on the members, otherwise fallback to `*self = other.clone();`. Ask yourself if
+you really need this.
+
+# Custom bound
+As most other traits, `Copy` and `Debug` support a custom bound on container
+and fields. See [`Debug`'s documentation](Debug.md#custom-bound) for more
+information.
+
+# Limitations
+
+*rustc* can optimize `derive(Clone, Copy)` to generate faster, smaller code.
+So does *derivative*. But *rustc* does not know about `derivative(Copy)` and
+would not optimize `#[derivative(Copy)] #[derive(Clone)]`.
+To avoid that issue, you should avoid deriving `Clone` using *rustc*'s default
+`derive` and `Copy` using `derivative`. *derivative* will error if it detects
+that, but can't always do it.
+
+[`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
+[`clone_from`]: https://doc.rust-lang.org/std/clone/trait.Clone.html#method.clone_from