1. A method implemented by one or more computing devices, the method comprising: identifying values representing individual text characters in a string of one or more text characters to determine which human writing system is associated with the individual text characters; comparing the values to a table that associates subsets of values with individual human writing systems; determining that the values representing the individual text characters are within a particular subset of values in the table that correspond to a particular said human writing system; and designating that the particular said human writing system is associated with the string based on the values associated with the individual text characters being within the particular subset of values that corresponds with the particular said human writing system.