Another key benefit of trading is each of the participants under a cap has complete flexibility in how they reduce emissions.

CNN: Your ask the expert: Carbon trading

These are black box strategies that allow an investment manager complete flexibility to invest across the spectrum of strategies and products.

FORBES: Should You Invest Like Yale University?

Mr. JIM MAY (CEO, Air Transport Association): It has proven itself to give us flexibility, which enables us to complete flights, albeit on a delayed basis where before they would have been cancelled.

NPR: FAA Seeks to Cut Air Traffic Congestion

It suggests options that could range from complete deregulation - where schools could create their own pay systems - to limited flexibility, with maximum and minimum pay bands.

BBC: Michael Gove pushes for performance pay for teachers

While ruling out "a complete free-for-all" on public sector pay, the authors claim greater flexibility in wage rates would improve work standards.

BBC: Calls for regional pay in public sector