06/01/2004 Initial version
11/01/2004 Require gross margin to be increasing 1%/year, require gross margin > 20%
12/13/2004 Use only last 3 quarters instead of 8 to calculate gross margin trend; set max price as function of gross income and revenue growth rate
12/20/2004 Debt threshold also function of gross income; reverted gross margin trend calculation to use 8 quarters
New Max Price calculation as function of next year's projected gross income; require Operating Income to be positive and at least 10% of gross income
Change calculation of revenue, gross margin trends to be basd on last 4 quarters, not 8 (all calculations now focus on a 4-quarter trend)
09/26/2005 Fixed bugs in Operating Income calculation (very positive results in back testing)
10/31/2005 Loosened Operating Income growth/year from 5% of gross income to 1% (was too tight)
12/12/2005 Eliminate companies with very low inventories and receivables based on an empirical observation that these have a high distribution of poor businesses