Hello - since this is an open professional event, we ask is that players aim for a "golf/casual" kind of attire. That is - no jeans, sneakers, t-shirts, or hats. Nice pants and a collared shirt (or sweater) would be expected.
I'll work on getting this explained better and added to our website FAQ section. The amateur events have a much more relaxed dress code (basically, nothing offensive or "too revealing")
Hope this helps!
Allen