If query is of the form name='Y' then you can use the same X.Y syntax as is used for accessing structures. attachments[size>1024], DocumentForm[name!='Summary' AND value~'top secret'].value, DocumentForm.SummaryX[N] where X is an array and N is an integer number >= 0, gets the Nth element of the array Xattachments[3]X/Y accesses Y from the topic specified by the value of X. X must evaluate to a to