Cargo Features

[dependencies]
oid = { version = "0.2.1", default-features = false, features = ["std", "serde_support", "u32"] }
default = std

The std feature is set by default whenever oid is added without default-features = false somewhere in the dependency tree.

std default
serde_support = serde
u32

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.

serde serde_support?