These layers and be added or removed dynamically and you can change each layer as it has a track that lets you change it as a function of time by inserting keys at certain frames in the track.

NPP carries five science instruments designed to help researchers track everything from the ozone layer to ice cover, and to help them develop both long - and short-term forecasts.

The UDP layer of the stack keeps track of the quantities of the writes and ensures that when the receiver on the right gets the data through the socket, it arrives in the same quantities.