(a) (S-90) Adjustments based on established prices. Established prices may reflect industry-wide and/or geographically based market price fluctuations for commodity groups, specific supplies or services, or contract end items.

(c) (S-90) Adjustments based on cost indexes of labor or materials. These price adjustments may also be based on increases or decreases in indexes for commodity groups, specific supplies or services, or contract end items.