The quality of a compression method often is measured by the Peak signal-to-noise ratio.
These compression methods require very little effort to compress and decompress.
No compression method is applied to the source data.
A simple compression method is already used in high-speed facsimile transmission systems.
It is not just at the ends of words where compression methods can be applied.
Typically, a symbol will correspond to a character of text, but this is not required by the compression method.
It has varying effectiveness depending on the input data and compression method.
And it agrees on a compression method, if the client wanted that.
Interesting point, never thought about this as a compression method, but I guess it's true.
The format's open architecture allows additional future compression methods to be added to the standard.