Specialization for a unit with special name valid only for a specific quantity
<mp-units/framework/unit.h>
template<
    symbol_text Symbol,
    AssociatedUnit auto QS,
    /* implementation-defined */ auto PO>
requires (!Symbol.empty()) && (QS.dimension == detail::get_associated_quantity(U).dimension)
struct named_unit<Symbol, U, QS>
    : /* implementation-defined */
| Name | Description | 
|---|---|
| /* implementation-defined */ | 
| Name | 
|---|
| _base_type_ | 
| Name | Description | 
|---|---|
| _point_origin_ | |
| _quantity_spec_ | |
| _symbol_ | Unique base unit identifier | 
The same as the above but additionally limits the usage of this unit to provided quantities.
| Name | Description | 
|---|---|
| Symbol | a short text representation of the unit | 
| Unit | a unit for which we provide a special name | 
| QuantitySpec | a specification of a quantity to be measured with this unit |