Cargo Features

[dependencies]
decimal = { version = "2.1.0", default-features = false, features = ["ord_subset", "rustc-serialize", "serde"] }
default = ord_subset, rustc-serialize, serde

These default features are set whenever decimal is added without default-features = false somewhere in the dependency tree.

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

ord_subset default
rustc-serialize default
serde default