FHIR-50428 - relax language on attachment url

Author: gotdan

input/pagecontent/export.md

@@ -723,7 +723,7 @@ Specifies the format of the file being requested.
 
 ##### Attachments
 
-If resources in an output file contain elements of the type `Attachment`, the server SHOULD populate the `Attachment.contentType` code as well as either the `data` element or the `url` element. When populated, the `url` element SHALL be an absolute url that can be de-referenced to the attachment's content.
+If resources in an output file contain elements of the type `Attachment`, the server SHOULD populate the `Attachment.contentType` code as well as either the `data` element or the `url` element. If the data element is not populated and the url element is populated, the url element SHALL be an absolute url that can be de-referenced to the attachment's content.
 
 When the `url` element is populated with an absolute URL and the `requiresAccessToken` field in the Complete Status body is set to `true`, the url location must be accessible by a client with a valid access token, and SHALL NOT require the use of additional authentication credentials.  When the `url` element is populated and the `requiresAccessToken` field in the Complete Status body is set to `false`, the url location must be accessible by a client without an access token.