Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

In multi-source queries, is it feasible to specify the type of attributes to be returned?

Yes, you can use return, it is an arbitrary expression. So, whatever you want to return from the “from,” you can.

For example

define "Encounter with Assessment Result":

from

"Valid Encounter" Encounter,

["Assessment, Performed": "Specified Assessment"] Assessment

where Assessment.result in "Specified Assessment Result Valueset"

and Assessment.relevantDatetime during Encounter.relevantPeriod

return Encounter