About PRO role "The  Principal  Race  Officer  shall  serve  as  the  lead  World  Sailing  Race  Officer,  and  is  responsible for racing  on  all  course  areas."
You find the Role definition in 2 World Sailing documents:

There is nothing to add to Gianluca's answer as he refers to the correct documents regarding the role of a principal race officer.

@Thomas: In your question you are not talking about a principal race officer (PRO) but a Course Race Officer or simply a Race Officer who is responsible for his/her race course. However, I see the role of a (Course) Race Officer in a more differentiated way than just 'pulling the flaggs or push the horn button'. The Race Officer is responsible for everything on the race course regarding race management.

A PRO (as World Sailing defines it) is in charge of multiple race circles and functions like a corporate Chief Executive Officer - they have the high-level view to ensure consistency across the various race circles and provides direction to the individual Race Officers in charge of the race management of their individual circles.  Often, they must be consulted when making a significant race management decision (abandonment, no more racing today, etc.)

A Race Officer / Course Race Officer functions like a Chief Operating Officer for a single course - they may take on a specific high-level task (course geometry, communications), but often these tasks are delegated to others.  Confusingly, in the US, these are called "PROs."

OK, follow-up question - Do WS policies and/or guides, specifically the ones mentioned above, have the status of Rules or Regulations designated by WS (Definition of Rules (b))? I only see RRS 90 as defining the duties and obligations of the Race committee, there is no definition or requirement for who does what on the RC. The hierarchy and responsibilities of the personnel is different at different events, from WS championships/World Cup/Olympic level all the way to Wednesday Night Round-the-buoys fun. An advantage to this PRO/CRO being on the signal boat is that it rarely moves and is not responsible for the physical movement of marks, precluding the duties of anchor-hauling.

Remember there's a difference between a race officer and a principal race officer.  A race officer runs one course, while a PRO runs. a number of. them in a regatta that needs more than one.  The definition that has been quoted relates to the PRO's job.  A race officer probably does normally have to pull up flags and sound the horn, make the tea and keep his team happy.  The PRO needs to be able to run around the various courses he is supervising. and make sure that each one is running smoothly.  If he's lucky he'll reach one or two just as the tea is being served1

David - in my humble experience the PRO of a multi-circle event is usually sequestered in a block building ashore, often without windows, on the radio fielding questions, coordinating things, and giving instructions. Judges get to bop around the race courses and check in with the various CROs. After racing, of course, the locations change and the Judges are sequestered in a protest room, and barring any disputes, s/he joins the rest of us at the appropriate hour for the then-appropriate beverage(s).

I think the heart of the original question is, given that the head Race Officer for a particular course or event is ultimately responsible for everything, are there guidelines that say that there are certain things that the head RO must attend to personally or do they have the latitude to delegate (while retaining ultimate responsibility) any or all functions as they please?

Tim-
I think you hit the nail on the head. There may be guidance as to who does what, but there are no Rules. The only Rule of which I'm aware is 90 (at the direction of the OA), and it only speaks to the Race Committee. Most OAs will appoint a RC Chair, and allow for great latitude as to their choice of the remaining members of the committee - often within somewhat limiting parameters (e.g. don't have 20 helpers for a 10 boat ILCA regatta). The chair, as with pretty much any committee, accepts responsibility for any and all actions of the entire committee. If the Chair is more comfortable following the fleet around, or finds the personnel not appropriate for a specific position, any good manager should be able to fill the role (flag waver, mark setter, etc.).  I prefer to take the blame for mistakes (and there are ALLLLLways mistakes) and credit the entire team for the successes, but that's just me. At the end of the day, we do what the guys putting the event together tell us to do.

I don’t think I have yet seen reference in this discussion to WS’s Race Officials Roles, Responsibilities and Competence doc, the latest version of which was published this month. While it is necessarily directed at international officials it does cover, as the title suggests, roles under discussion here, although it may not mention flags or windowless buildings. 

The original question asked for a definition, which I (mis?) read as a Rule, of what the PRO is responsible for and/or is supposed to do. Gianluca made reference to either the documents Nick mentions or similar (in that they're all WS documents) above. My immediate question (in my first post above) was if those documents, and/or the ones to which you refer if different, have the status of Rules under the definition Rules (b). If they do, a lot of ROs have been doing it wrong for a long time. Absent them being so, we make whatever resources we either are given or have rounded up get the job done to the best of our abilities. Our customers, the OA and ultimately the sailors, rely on us to do so.

That may well have been your question but the thread initiator asked for a definition of the role of the PRO. My response was to that question not yours. The documents are clearly not rules but there are plenty of rules that ROs need to abide by. Because our sport is so diverse hard and fast rules about who does what task would be impossible to formulate and in fact unnecessary as long as all the tasks are done. 

Like I said, sorta, I may have misread that, taking "definition" to mean a Rule. (Language barrier? Brits, 'Mericans, and yes even Aussies all speak somewhat different version of the same language - much like Spaniards, Cubans, and Puerto Ricans all speak different versions of their same language!) I agree with you that hard and fast rules would be unwieldy at best, and as long as it all gets done we have done a good job.  Best, -- Carl

Thank's a lot to everybody! Just to clarify my request: My main issue is the course officer, sorry about the wrong wording. So far I have learned, that the responsibility of the "head of the race comittee" is not a subject to a WS rule, which I believe is advantage. This leaves us to organize ourselves the way that best suits the local requirements.  

Thomas, I think that’s right .. there is no “rule” that says you can’t organize your OA/event to fit your needs. 

That said, people who you might rely upon may be accustomed to fitting into the established roles and structures as outlined in the comments and documents our members have provided here.  This is just to say that by leveraging what is established, developed and documented, you might avoid some confusion.