I am not able to identify the use of @keys at an element that is actually a
conref. In case of a conref, the @href may be generally missing as that shall be
derived from the referenced element.

Say for example, in a map there is topicref element which is actually a conref
to a topicref element in another map.

In map1.ditamap: <map> ....... <topicref id="tr-01" keys="TR01" href="abc.dita"/> ....... </map>

In map2.ditamap: <map> ....... <topicref id="tr-02" keys="TR02" conref="map1.ditamap#tr-01"/> ....... </map>

What shall the key TR02 resolve to? As I understand, that resolves to nothing. Also, is there any specific use of such a key in a conref element, apart from
defining a key that points to nothing. I am not ruling out the cases where such
an element carries an @href as well. But in that case, the purpose of conref is
undermined.

Regards,