<UNION>, why?

Hi,

while I know the XForm Data Model draft I revere to is outdated,
I'd still like to know what <union> is intended for.

IMHO it mixes UserInterface stuff, into the data model:

<union name="weekday">
  <string range="closed">
    <value>Monday</value>
    <value>Tuesday</value>
    <value>Wednesday</value>
    <value>Thursday</value>
    <value>Friday</value>
    <value>Saturday</value>
    <value>Sunday</value>
  </string>
  <number min="1" max="7" integer="true"/>
</union>

In the database where i store me xml data in, i definitely do not want
to have one record with <weekday>1</weekday> and another with
<weekday>Monday</weekday>. And I don't se why anybody would like to.

So, what is <union> intended for?

Cu,
    Goetz.