The Consumer Data Industry Association. is an international trade association, founded in 1906, that represents consumer information companies that provide fraud prevention and risk management products, credit and mortgage reports, tenant and employment screening services, check fraud and verification services, and collection services.
From page 2-7 of the Manual, the instructions for reporting REVOLVING credit cards such as the Capital One credit cards ("open" accounts are paid in full each month and don't have a pre-set limit, such as the American Express card and utility accounts):
From page 2-9 of the Manual, the instructions for the reporting of revolving Retail Accounts such as the Target store Guest Card (Target now reports the limits):
There is NO question that the credit LIMITS are to be reported. Note the word "requirements" above each table, there's nothing optional.