Is a single <Schema> element adequate?

[Tommy Lindberg <tommy.lindberg@gmail.com>]

The <Schema> element in DocumentBaseType and SignatureObject allows
for the optional
transfer of a single XML Schema. This seems inadequate for some use
cases such as
verifying a signed XML instance that pertains to a schema that in turn imports
additional schemas.

I understand that policies and profile's may allow a DSS service to be
configured
to "support" a set of schemas, effectively elliminating the need for
inband transfer.
However, when this is not the case I am thinking that the ability to
do something
similar to the following instance fragment, would be useful.

<dss:Schemas>
  <dss:Schema>...</dss:Schema>
  <dss:Schema>...</dss:Schema>
  ...
</dss:Schemas>

Regards,
Tommy