20. The tangible computer-readable medium of claim 18 , wherein the form attribute has a value of at least one of area, line and arrow.
20. The tangible computer-readable medium of claim 18 , wherein the form attribute has a value of at least one of area, line and arrow. 21. The tangible computer-readable medium of claim 20 , wherein the form attribute has a value of area and the meaning attribute identifies a meaning of area.