条形码技术的基础是识别编码在特定尺寸的条形码和空间中的模式。以条形码形式编码信息的方法有很多，称为符号学。代码128就是这样一种符号。定义将字符转换为条形和空格模式的规则，以及每个符号的其他基本特征，称为符号规范。 过去，符号规范是由多个组织制定和发布的，导致某些情况下对某些符号的要求相互冲突。 条形码设备制造商和条形码技术用户需要公开的标准符号规范，在开发设备和软件时可以参考这些规范。 ISO/IEC 15417:2007规定了被称为代码128的条形码符号的要求。它指定了代码128符号特征、数据字符编码、尺寸、解码算法和应用程序定义的参数。 它为代码128符号指定符号标识符前缀字符串。

The technology of bar coding is based on the recognition of patterns encoded in bars and spaces of defined dimensions. There are numerous methods of encoding information in bar code form, known as symbologies. Code 128 is one such symbology. The rules defining the translation of characters into bar and space patterns, and other essential features of each symbology, are known as the symbology specification. In the past, symbology specifications were developed and published by a number of organizations, resulting in certain instances in conflicting requirements for certain symbologies. Manufacturers of bar code equipment and users of bar code technology require publicly available standard symbology specifications to which they can refer when developing equipment and software. ISO/IEC 15417:2007 specifies the requirements for the bar code symbology known as Code 128. It specifies Code 128 symbology characteristics, data character encodation, dimensions, decoding algorithms and the parameters to be defined by applications. It specifies the symbology identifier prefix strings for Code 128 symbols.