Guest7 wrote:If something is xm² is that always x square metres or can it also be x metres all-squared. Do you have to stop it being ambiguous by stating x(m²) and (xm)²?
It is always x square meters. Section 9.6 of NIST SP811 has additional info, but the exponent always goes with the unit, including any attached prefix which is inseparable.
In words an exponent of 2 would normally be stated as "squared" after the unit. An exception is made for m², where square meters is also permitted, and is probably more common.