Automatically adjust spaces between symbols in words or phrases to fit them into a specified length. Any chain of symbols (including spaces) in the current font may be treated.

Commands \track{<length>}{<string>} (add space <length>, which may be <0, after each symbol of <string>), \fittrack{<length>}{<string>} (make <string> fit into width <length>, which may be smaller than the original width) and \ratiotrack{<ratio>}{<string>} (as \fittrack, with <length> replaced by <ratio> of the natural length of <string>).

See also letterspacing soul textfit.

The author is Dmitry A. Glazkov.