13. A keyboard apparatus in accordance with claim 12, wherein the polygraphic code sequence represented by said polygraphic keys are those code sequences selected from all possible code sequences generally having the highest stroke saving function values.
13. A keyboard apparatus in accordance with claim 12, wherein the polygraphic code sequence represented by said polygraphic keys are those code sequences selected from all possible code sequences generally having the highest stroke saving function values. 16. A keyboard apparatus in accordance with claim 13, wherein each monographic key locates in the middle rank remote from the central keys thereof.