A command used read the schema definition from eDirectory or the application. Drivers are not currently required to implement it, but this might change. Drivers are required to implement the DriverShim.getSchema() method, which does exactly the same thing.
A response to <query-schema> should be a <schema-def>.
A response to <query> should also include a <status> indicating whether or not the <query> is processed successfully.
<query-schema/>
( operation-data ? )