Parity's Envelope Struct

message.rs

pub struct Envelope {
	/// Expiry timestamp
	pub expiry: u64,
	/// Time-to-live in seconds
	pub ttl: u64,
	/// series of 4-byte topics.
	pub topics: SmallVec<[Topic; 4]>,
	/// The message contained within.
	pub data: Vec<u8>,
	/// Arbitrary value used to target lower PoW hash.
	pub nonce: u64,
}