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diff --git a/mingling_core/src/asset/metadata.rs b/mingling_core/src/asset/metadata.rs
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+/// Provides metadata for an Entry.
+///
+/// Any type can be attached to an Entry as metadata, allowing the program to
+/// carry compile-time-typed, arbitrary description data alongside each
+/// registered entry. The [`Metadata`] trait bridges an Entry type (`Self`) to
+/// an arbitrary metadata type `DataType`.
+///
+/// # Manual impl
+///
+/// It is recommended to use the `#[metadata(Entry)]` attribute macro from
+/// [mingling_macros](https://crates.io/crates/mingling_macros) to implement this
+/// trait and register the entry via `register_metadata!`.
+///
+/// If you need to implement it manually, you can refer to the following
+/// example:
+///
+/// ```
+/// # use mingling_core::MockProgramCollect as ThisProgram;
+/// # use mingling_core::Metadata;
+/// struct EntryGreet;
+/// struct MyInformation {
+///     name: String
+/// }
+///
+/// impl Metadata<MyInformation> for EntryGreet {
+///     fn init_metadata() -> MyInformation {
+///         MyInformation { name: "Greeting".into() }
+///     }
+/// }
+///
+/// // Register the MyInformation metadata for EntryGreet using `register_metadata!`.
+/// // mingling::macros::register_metadata!(EntryGreet, MyInformation);
+/// ```
+pub trait Metadata<DataType> {
+    /// Initializes and returns the metadata value of type `DataType` for this entry.
+    fn init_metadata() -> DataType;
+}