All children of required "offline" element are optional in PhysicalDistributionType
in PhysicalDistributionType, the "offline" element is required, but all its
children are optional; thus if the user does not provide any offline metadata,
the offline element will be empty.
#4 Updated by Margaret O'Brien about 14 years ago
This bug applies to the DistributionType defined in eml-resource.xsd, since that is the base type. In EML-2.1.0, the PhysicalDistributionType (defined in eml-physical.xsd) is an extension of res:DistributionType. Both types should require mediumName.