//! The bottom layer: credential primitives, framing checksums, configuration,
//! address resolution, and the file primitives the durable stores build on.
//!
//! Nothing here depends on another `pb-mapper` crate, which is what makes it
//! the bottom. `DataLenType` lives here rather than with the message framing
//! that names it, so that `checksum` and `error` can use it without depending
//! on the protocol layer.
/// The width of the length prefix on a framed message.
pub type DataLenType = u32;