ByJohn S. McClenahen U.S. Treasury Secretary Paul H. O'Neill continues to talk tough on the topic of tax simplification. "The tax code is an abomination. It runs unnecessarily to thousands of pages," he says. O'Neill has just released the first of what he promises to be series of Treasury proposals to make the tax code simpler and fairer -- this one dealing with individual taxes rather than business taxes. In place of the confusion of current definitions, the proposal provides a single definition of a child -- based on relationship, residence and age -- to determine eligibility for the dependency exemption, child tax credit, child and dependent care tax credit, head of household filing status, and earned income tax credit. The proposal is less than a page long.