An undermount sink's "reveal" refers to the amount that the countertop extends over the edge of the sink.

A positive reveal means that the lip of the sink sticks out slightly beyond the edge of the countertop. (revealing the sink)

A negative reveal means the countertop surface overlaps the edge of the sink.

I think those terms are interchanged often, sometimes people refer to the counter extending over the sink as a positive reveal. It doesn't matter what you call the "reveal" as long as you and your fabricator each understand exactly what you want -- either the sink extending beyond the counter, or the counter extending beyond the sink OR, the counter being equal to the sink (neutral).

As for the Orca (my choice in sinks too) you might run into trouble with accessories if you specify a large positive reveal -- countertop extending beyond the sink enough to interfere. My sink is not installed yet. The only photos I've seen of the cutting board seem to show it sitting on top of the counter anyway.

Don't let the fabricator rush you. He may be ready, but too bad. You get one chance to do this right. Call Franke if you must to inquire specifically.

Here's a link to a thread with photos

Here is a link that might be useful: Orcas

Thanks, athomesewing, for the info and the thread.

I called Franke, and I am shocked. The rep said they can not say that the accessories will work unless you have the accessories on hand when the cutting is done. I said something like, "So you're saying that even if the fabricator correctly uses the template you provide, you don't promise that the accessories will work?" and she agreed.

For these prices, I expect better. I'm calling around trying to find a cutting board in stock, but so far, no luck.