ame rules. An exception is made for quantities for
        which the unit reduces to dimensionless; in this case, implicit conversion
        to the underlying value type is allowed via class template specialization.
        Quantities of different value types are implicitly convertible only if the
        value types are themselves implicitly convertible. The <span class="underline"><code class="computeroutput"><a class="link" href="../boost/units/quantity.html" title="Class template quantity">quantity</a>