Questions in case of multipul Types for one Service

[OHTSUKA Ko-hei]

Question.

On OpenID, extensional protocol shows in Yadis,

<Service>
  <Type>http://openid.net/signon/1.2</Type>
  <Type>http://openid.net/extensions/sreg/1.0</Type>
  <URI>http://www.myopenid.com/server</URI>
</Service>

But on LID, many Yadis example shows like

  <xrd:Service priority="1">
   <xrd:Type>http://lid.netmesh.org/minimum-lid/2.0b8</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>
  <xrd:Service priority="2">
   <xrd:Type>http://lid.netmesh.org/sso/2.0b8</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>
  <xrd:Service priority="3">
   <xrd:Type>http://lid.netmesh.org/sso/1.0</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>
  <xrd:Service priority="4">
   <xrd:Type>http://lid.netmesh.org/relying-party/2.0b8</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>
  <xrd:Service priority="5">
   <xrd:Type>http://lid.netmesh.org/traversal/2.0b8</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>

So, I have two question.

1. If there are no priority differences among every services,
   upper xrds meaning may be same as

  <xrd:Service>
   <xrd:Type>http://lid.netmesh.org/minimum-lid/2.0b8</xrd:Type>
   <xrd:Type>http://lid.netmesh.org/sso/2.0b8</xrd:Type>
   <xrd:Type>http://lid.netmesh.org/sso/1.0</xrd:Type>
   <xrd:Type>http://lid.netmesh.org/relying-party/2.0b8</xrd:Type>
   <xrd:Type>http://lid.netmesh.org/traversal/2.0b8</xrd:Type>
   <xrd:URI>http://mylid.net/foo</xrd:URI>
  </xrd:Service>

   Is this understanding right?

2. I have little knowledge about LID, so writing below is maybe
   misunderstanding,
   But I think LID's each protocols (sso,relying-party,traversal,
   etc...) are used for different usecases, so adding different
   priorities to them is nonsense.

   Though seeing XRD files examples including LID, almost all
   examlpes adding different priority to each LID protocol.

   Are there any reason to do like this?