By the book, I think it needs to be in the SIs. Unless you consider a starting mark to be a rounding mark, you wouldn't comply with RRS 33 by flying C at the start. This doesn't seem to be the intent of the RRS as I read it (otherwise, why would they say "starting mark" vs "rounding mark" vs "finishing mark"?).

This is especially true since you'll want to use something other than the C flag, and you'll need to explain that (in writing, not just at the skippers meeting, ISAF cases for that too).

As Matt mentioned, this was mentioned in a National RO exam (there were a LOT of other problems presented with that case, the flag was only part of the issue). I think it just highlighted a point where too much is too much...

Mike