if a sequence can be tokenized, that is, separated into "words", an unknown human language may be distinguished from many other data sequences by the frequency distribution of the tokens. human languages conform to a zipfian distribution, while many (but not all) other data sequences do not. it has been proposed that an alien language also might conform to such a distribution (). when displayed in a log-log graph of frequency vs. rank, this distribution would appear as a somewhat straight line with a slope of approximately -1. seti scientist laurance doyle explains that the slope of a line that represents individual tokens in a stream of tokens may indicate whether the stream contains linguistic or other structured content. if the line angles at 45°, the stream contains such content. if the line is flat, it does not.