am hearing that it is best practice to allow both scenarios – the “empty
element” and the “omitted element” – in documents that are provided.
don't think there is any consensus on this.
My own preference is to model absent or not-applicable data by
omitting the relevant element or attribute, using elements/attributes
that exist but have an empty string as their value only for cases where this
has some real meaning.
There is of course a third way to represent absent information,
namely to use the xsi:nil attribute, but I've never met anyone who thinks that
is a good idea.