一种插入一些无意义字符的处理方法。例如，在一个字段、记录或固定长度数据块的不用部分插入空字符、零或空格。

The process of inserting meaningless characters, such as null characters, zeros, or spaces, into the unused portions of a field, record, or fixed- length block of data.

具有固定长度控制的可变记录格式

variable with fixed-length control record format; variable with fixed-length control record format

密码一种密码系统，其中固定长度的明文里的单元，通常为字母，被任意倒置或按事先确定的符号系统替换

A cryptographic system in which units of plain text of regular length, usually letters, are arbitrarily transposed or substituted according to a predetermined code.