Validating schema vs. non validating schema

Hi All,

What do you prefer?

<length uom="...">
<weight uom="...">
where uom=m|mm|kg|g

<length length-uom="...">
<weight weight-uom="...">
where length-uom=m|mm and weight-uom=kg|g

Thanks for your comments,

Regards,

Patrice Krakow