Under the definitions of Tier 1, Tier 2, and Tier 3, there is a statement that reads: "The default contract length for renewable energy procurement is 10 years. Contract lengths less than 10 years may be pro-rated." It is unclear to me, and others I've checked with, what this sentence means and what exactly it applies to (for example, I would assume it does not apply to Tier 1, which has nothing to do with renewable energy procurement). 

Can someone explain how this statement relates to how a project team is supposed to ask for quotes and document credit compliance (assuming for Tier 2 and Tier 3)?