2. The method of claim 1 , wherein producing the set of proximity scores includes: producing a first subset of proximity scores by performing a first subset of proximity checks using the set of linguistic characteristics, and the text; and producing a second subset of proximity scores by performing a second subset of proximity checks using the set of linguistic characteristics and the set of reference documents for each time period.
4. The method of claim 2 , further comprising: the first subset of proximity scores and second subset of proximity scores includes a first proximity score determined from a third proximity check comparing how close the time periods of the linguistic characteristics are; and the first subset of proximity scores and second subset of proximity scores further includes a second proximity score determined from a fourth proximity check comparing the how close a placement of the linguistic characteristic is in the text to other linguistic characteristics.