[jats-list] Strange top-level elements permitted in the RNG version of Blue

["Imsieke, Gerrit, le-tex gerrit.imsieke@xxxxxxxxx" <jats-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

I discovered that the Relax NG schemas of the Publishing (Blue) 
customization permit top-level elements that are not part of Blue:

<start>
  <choice>
    <ref name="article"/>
    <ref name="rp"/>
    <ref name="overline-start"/>
    <ref name="unstructured-kwd-group"/>
    <ref name="underline-end"/>
    <ref name="underline-start"/>
    <ref name="x"/>
    <ref name="overline-end"/>
  </choice>
</start>

In the Green and Pumpkin RNG schemas, there's only this:

<start>
  <choice>
    <ref name="article"/>
  </choice>
</start>

I haven't checked all 4 variants of each customization, I only took two 
samples each.

Is there a reason for this, or did this happen by mistake?

Gerrit