Environmental policy of the United States from the sun. Chlorofluorocarbons (CFCs), which were used beginning in the 1930s in a number of important areas, were determined in 1974 to be responsible for much of the depletion of the ozone layer. Four years later, the EPA and FDA banned CFCs in aerosol cans. As research in the 1980s indicated that the problem was worse than before, and revealed a controversial massive hole in the ozone layer over Antarctica, three international agreements were made to reduce the ozone-damaging substances- the Vienna Convention, the 1987 Montreal Protocol, and a third agreement in 1990 in London. In the United States,
Separation of concerns 1989, Chris Reade wrote a book titled "Elements of Functional Programming" that describes separation of concerns: Reade continues to say, Separation of concerns is crucial to the design of the Internet. In the Internet Protocol Suite, great efforts have been made to separate concerns into well-defined layers. This allows protocol designers to focus on the concerns in one layer, and ignore the other layers. The Application Layer protocol SMTP, for example, is concerned about all the details of conducting an email session over a reliable transport service (usually TCP), but not in the least concerned about how the transport service