What does it mean to ask a private business to report their costs "on a fully loaded basis"?
And then to ask them to "please indicate the fully loaded basis for which the costs are reported"?
Reporting costs on a fully-loaded basis means that the business should report costs directly and indirectly associated with its product and the relevant indirect costs, e.g. overhead, indirect charges, etc. If you're looking at a company in general, the fully-loaded cost basis of the firm is essentially all costs related to the product(s) it offers.
In economics/accounting 101 terms, reporting costs on a fully-loaded basis means reporting both the fixed and variable costs associated with production. Fixed costs are costs that remain constant regardless of how much the firm produces, e.g. general overhead like rent, managers' salaries, etc. while variable costs are per-unit costs that may change as the firm increases or decreases production, e.g. the cost of materials, hourly wages, etc.