How is the excess field populated in the F0627?

I am reviewing Workers Compensation with a client and it seems the Excess fields are populated with all applicable wages for the month. I thought the Excess field was for anything over the Workers Compensation limit. What determines how this field is populated?

I should note that the person we were looking at was a WY employee who would have a six digit code in the 00|W UDC second description field and I read in one of your documents on support that if there is a code in the second description field the system ignores limits. If that is the case then is it populating all wages if you have a value in the second description of the UDC table?