//! Unit assignment, prefixes and conversion-based units.
//!
//! `IfcUnitAssignment` sets the model's units; derived and conversion-based
//! units (imperial, US survey feet) must be resolved before a value means
//! anything.
//! ## Internal split
//!
//! - `assignment.rs`: project unit context.
//! - `si.rs`: SI prefixes/dimensions.
//! - `conversion.rs`: conversion-based units.
//! - `derived.rs`: derived dimensions/elements.
pub use ;
pub use ;