To compact data by combining parts of the data,for example,to transform a two-word alphabetic key into a one-word numeric key by adding the numeric equivalents of the letters.

• 通过将数据的某些部分进行组合来压缩数据，例如，通过将一些字母的数字等值相加，可把两个字长的字母键词变换为一个字长的数字键词。