4. The document matching method of claim 3, wherein the reduced character shape code comprises at most 2.sup.n character shape codes and wherein the reduced binary data string converting steps each comprise converting each reduced character shape codes to a different n-bit binary number, wherein n is a positive integer.
3. The document matching method of claim 1, wherein the character shape code converting steps each comprise converting the plurality of documents and the test string using a reduced set of said character shape codes, wherein said reduced set of character shape codes is a subset of said plurality of said character shape codes.