FQL

Two canonicals

If you want to filter multiple resources by a small set of canonicals

from StructureDefinition
    where url in ('http://example.org/fhir/StructureDefinition/xxx' | 'http://example.org/fhir/StructureDefinition/yyy')
select
    Name: name,
    Description: description,
    Version: version,
    Status: status,
    URL: url