RE: [xml-dev] Please no UOM (was Re: maps)

> > These types of constraints tend to fall into the realm of "business
> > rules", and in no way belong in a data schema language
> 
> It has been standard practise from the beginning of markup languages
> to accept multiple units of measurement, such as inches, pica, cm.
> 

Right.  Serializing unit-of-measure values lexically in markup is fine.
It's when people start setting constraints on the actual value space
that the problems come in.