ET meaning in Messaging ?

Emissions trading is a market-based approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). Carbon emission trading for CO
2 and other greenhouse gases has been introduced in China, the European Union and other countries as a key tool for climate change mitigation. Other schemes include sulfur dioxide and other pollutants.

In an emissions trading scheme, a central authority or governmental body allocates or sells a limited number of permits that allow a discharge of a specific quantity of a specific pollutant over a set time period. Polluters are required to hold permits in amount equal to their emissions. Polluters that want to increase their emissions must buy permits from others willing to sell them.

Emissions trading is a type of flexible environmental regulation that allows organizations and markets to decide how best to meet policy targets. This is in contrast to command-and-control environmental regulations such as best available technology (BAT) standards and government subsidies.