It is not currently possible.  Perhaps if there were a compelling reason, we should add it.  Anyone else use the hearing schedule for notification of witnesses?

RRS L16.3 states 

It is not "compelling" but a rather good reason to do it, even though it is the responsibility of parties to make sure their witnesses attend the hearing.

I added witnesses to the public schedules.  Any witnesses included on the hearing request will be shown on the schedule.

I have tried in in one event.  Just a couple of columns need be added to hearing schedule notice - Protestor, Protestee, Witness.

But, this was a "physical/paper" notice displayed on Regatta Notice Board, not through RRS.org

Paul, does it work only if the witness is stated in a "protest" and not in a "decision"?

OK, thank you, but now it is possible to see the witnesses in the hearing shedule only if "create a protest" and not if "create a decision". I think better to have both possibilities because it is permitted to open a hearing by "create a decision" without to open "create a protest".

The thought was that the witnesses indicated on the Hearing Decision would only be those that appeared during the hearing.  But I changed the logic a bit.  When a Hearing Request is submitted with witnesses indicated, it now pre-populates the witnesses in the Hearing Decision. The judges can then edit that as they like (add or remove) and that data is what is shown n the Hearing Schedule.  Then during the hearing, the witnesses indicated can be edited to show who actually did give testimony. This change loads up the witness field with some hidden logic, but I think it reflects how judges actually work, so it should be intuitive.  Marco, thanks for the feedback on this.  I think it adds to the utility and communicates better with the competitors.

This for sure is a good change, Paul.

In conclusion I'd like to confirm the followings.
Witnesses are not required to attend the hearing by any rules, are they?
RRS L16.3 don't have a compelling force.  
Therefore even If protest notices are posted, the witnesses can refuse to attend the hearing. 

Well, I would respond that none of the parties or the witnesses are required to attend a hearing.  I'm sure that's not what you mean though. The jury can of course proceed with a hearing without a party or any parties present for that matter.  The possibility of a penalty as a result of the hearing is the only "compelling force" that would compel a party to attend.  And generally, a witness has nothing at stake, so there is nothing compelling them to attend other than their desire to contribute to the hearing.  But there is always the chance the jury may find the witness broke a rule, in which case they witness would then be named as a party.  But that would start the whole notice process over again so it doesn't really compel a witness to attend.  So to answer your question,  no, witnesses are not required to attend even if they are notified on the schedule.  But then, neither are the parties.