How does a optimized link look like?

Hello everyone,

I was asking myself what's the best way to make the most perfekt link element.

For example:

I want to save cars and link them with their owners (Recipients).

So I got this schema:

<srcSchema _cs="Cars (ahae)" created="2017-01-30 16:05:06.705Z" createdBy-id="0" entitySchema="xtk:srcSchema"

           img="xtk:schema.png" label="Cars" labelSingular="Car" lastModified="2017-02-08 14:00:52.599Z"

           mappingType="sql" md5="9868DCF2A5ECFF7A84423884449700D1" modifiedBy-id="0"

           name="car" namespace="ahae" xtkschema="xtk:srcSchema">

  <createdBy _cs="Administrator (admin)"/>

  <modifiedBy _cs="Administrator (admin)"/>

  <element label="Cars" labelSingular="Car" name="car">

    <attribute label="CarID" length="20" name="carID" type="string"/>

    <attribute label="Name" length="20" name="name" required="true" type="string"/>

    <element label="Owner" name="owner" target="nms:recipient" type="link"/>

          <join xpath-det="@id" xpath-src="@CarID">

    <key internal="true" name="carID">

      <keyfield xpath="@carID"/>

    </key>

  </element>

</srcSchema>

What is the best way to optimize this Link?

Best regards,

Alex