HTML can be output using normal <item> tags with the copyHtml attribute.

By the way, I see you're a member of QP's team. I'd suggest talking with some of the local Trak technical specialists -- they are experts in Zen reports.

Ensemble's ESB components can accept an HTTP request and pass it through to a downstream system.

Here's a link to the ESB section of the Ensemble docs.

You can see this table in the management portal if you tick the "System" checkbox to display Caché system tables.

You can query the table you found like this:
select * from INFORMATION_SCHEMA.TABLES

I note from the docs you linked that this will only show tables that the current user has privileges for.

If you plan on doing frequent searches against a specific HL7 segment/field, you can speed up the searches significantly by using Ensemble's "search tables" mechanism for adding an index for that field.

http://docs.intersystems.com/latest/csp/docbook/DocBook.UI.Page.cls?KEY=...

Fields indexed in the search table are listed in the dropdown box on the message viewer search, or can be queried using SQL by joining EnsLib_HL7.SearchTable:

select msg.ID,msg.TimeCreated,
       msg.DocType,
       msgHdr.SourceConfigName,
       msgHdr.TargetConfigName,
       msg.RawContent 
from EnsLib_HL7.SearchTable srchTbl
join enslib_hl7.message msg on msg.id=srchTbl.docid 
join Ens.MessageHeader msgHdr on msgHdr.MessageBodyId=srchTbl.docid
where  (srchTbl.propid=(select propid from Ens_Config.SearchTableProp where classextent='EnsLib.HL7.SearchTable' and name='PatientSSN')
       and srchTbl.propvalue = '123-25-4612')
       and msgHdr.SourceConfigName='HL7.File.In'