Data represented by the punching of single holes in each column of a field on a punched card. For example, alphabetic characters and other symbols may be punched as two holes per column.; 通過在卡片上某個字段中的各列穿單孔來表示數(shù)據(jù)的一種方法。字母字符和其它符號可能要 在各列上穿雙孔。