... cl, j is a space character and ci,j is a space character F2 F3 F4 ci,,j is an alphanumeric character or a special character, and ci,j is a space character ci,,j is a space character, and ci,j ... cij is a space character and ei,jq_ 1 is a space character; or ci,j is a special character and ci,j+l is a special character cij is an alphanumeric character or a special character, and ci,j+l ... ci,j+l is a space char- acter F3 ci,j is a space character, and cl,j+l is an alphanumeric character or a special char- acter Table 2: Feature values for table column and H' = Ci',1...