Suppose you want to determine how LEED, the green building rating system, effects marketing opportunities for your product. This used to be fairly simple to determine, as there was just one version of LEED and you could quickly scan the list prerequisites and credits to see which related to your product.

It is a bit more complicated now:

There are Multiple Versions of LEED for different types of projects, including New Construction, Existing Buildings, Core and Shell, Schools, etc. Many of these versions have the same or similar credits, but there are differences that have to be understood.
Then you get to look at the Pilot Credits, credits that can be incorporated on a trial basis into projects so USGBC can test new ideas. This list is updated frequently.
Regional Priorities give extra credit to some LEED credits for addressing especially sensitive regional concerns. This would be useful to plan regional sales efforts, but the data has to be teased out Zip Code by Zip Code.
And there are Credit Interpretation Reports, responses to questions by LEED users that can expand upon or change the scope of a credit.
(Don't forget to check the Errata.)

If you have a question about LEED, don't bother calling USGBC. Their "customer service" people are totally unfamiliar with LEED. When I finally got a phone number for the corporate office, the switchboard there immediately connected me back to customer service.

To where does all this LEED? (Pardon the pun.)

If you have difficulty understanding LEED, don't worry; in less than a year the next edition of LEED will be issued, and you can begin your LEED attempt to understand the system all over again.

Illustration from Daily Journal of Commerce.