1. In apparatus for automated linguistic expression substitution, the improvement comprising A. first input means for inputting, into said apparatus, a suspect expression signal representative of a linguistic expression consisting of characters, B. second input means for inputting, into said apparatus, an alternate expression signal representative of a permissible linguistic expression consisting of characters, C. comparison means, connected to said first and second input means, for comparing said suspect expression signal with said alternate expression signal and for producing a disparity signal numerically representative of differences between a spelling of the linguistic expression represented by said suspect expression signal and a spelling of the linguistic expression represented by said alternate expression signal, said comparison means including means for detecting disparity types representative of (i) transposition of character order, (ii) deletion of a character, (iii) an unmatched character, and (iv) differences in expression character length, occurring between said compared expression signals, said comparison means further including means responsive to the detection of said disparity type for producing a signal indicative of the numerically-weighted structural significance of that type, and D. selection means, connected to said comparison means and responsive to a numerical value represented by said disparity signal, for selectively determining said alternate expression to be substitutable for said suspect expression and for producing an output signal indicative thereof.