You're right, that appears to be the right field. However, when I try to update it with this request:
I get the following error:
"errorMessage" : "An internal error has occurred",
"errorMessageKey" : "errors.internalError"
However, I don't think I actually need to set this field for what I'm trying to accomplish. After some more testing, I've gotten closer to the root of the issue. I've created a new topic for this issue: viewtopic.php?f=104&t=24574