Fix epochs schema to resolve double nesting of sdpi:Epoch element.

[PaulMartinsen]

📑 Description

Resolves TimeStampVersion.xsd schema bug in #520 to avoid nesting sdpi:Epoch found by Leon.

☑ Mandatory Tasks

The following aspects have been respected by the pull request assignee and at least one reviewer:

• Changelog update (necessity checked and entry added or not added respectively)
• Pull Request Assignee
• Reviewer

[d-gregorczyk]

I suppose, this is a BICEPS extensions, isn't it? It lacks the necessary MustUnderstand attribute then.

It is recommended to add the optional attribute to the element that represents the extension rather than adding it to the type. That would result in "Epochs" being:

<xsd:element name="Epochs">
  <xsd:complexType>
    <xsd:complexContent>
      <xsd:extension base="sdpi:EpochsType">
        <xsd:attribute ref="ext:MustUnderstand" use="optional" />
      </xsd:extension>
    </xsd:complexContent>
  </xsd:complexType>
</xsd:element>

[PaulMartinsen]

There were a couple of other places where the MustUnderstand attribute was on the type and not the element so I fixed those too.

Do you think there is too much scope for understanding now? Perhaps the MustUnderstand is only needed on the containing Epochs element and shouldn't be separately available on individual sdpi:Epoch elements, for example:

<pm:State ActivationState="StndBy" LastSet="1733317200000" DateAndTime="1733328000000"
          DescriptorHandle="clk" StateVersion="15" RemoteSync="1" 
          xsi:type="pm:ClockState">
  <ext:Extension>
    <sdpi:Epochs Version="5" ext:MustUnderstand="False">
      <sdpi:Epoch Version="4" Timestamp="1733317200000" Offset="-PT3H" ext:MustUnderstand="True"/>
      <sdpi:Epoch Version="3" Timestamp="1733295600000" Offset="PT4H" ext:MustUnderstand="False"/>
    </sdpi:Epochs>
  </ext:Extension>
</pm:State>

[d-gregorczyk]

Found another one; sorry for the late review.