本规程规定了用于定时、控制、编辑和同步目的的电影胶片的数字代码格式和调制方法。这种做法还规定了代码与电影画面的关系。本规程中描述的代码与SMPTE 12M中描述的连续代码类似。本规程中描述了两种类型的代码。第一种类型C是连续代码，与SMPTE 12M中规定的连续代码非常相似。这种类型的代码可用于胶片在录制和复制时连续移动的情况。第二种类型的代码，类型B，是一个不连续的块- 类型代码，由数据块组成，每个数据块本身都是完整的，块之间有间隙。它的设计使代码可以在间歇胶片运动的设备上记录和播放，但仍然可以使用用于读取C型或连续时间代码的相同类型的电子设备进行解码。本实践中描述的代码可以在各种帧速率下使用，当前感兴趣的帧速率为每秒24、25和30帧。

This practice specifies digital code formats and modulation methods for motion-picture film to be used for timing, control, editing, and synchronization purposes. This practice also specifies the relationship of the code to the motion-picture frame. The codes described in this practice are similar to the continuous code described in SMPTE 12M. There are two types of codes described in this practice. The first type, type C, is a continuous code which is very similar to the continuous code specified in SMPTE 12M. This type of code can be used in situations where the film is moving continuously at the time of both recording and reproduction. The second type of code, type B, is a noncontinuous, block-type code, composed of blocks of data, each complete in itself, with gaps between the blocks. It is designed so that the code may be recorded and played back on equipment with intermittent film motion but still be decoded with the same type of electronic equipment used to read the type C or continuous time code. The codes described in this practice can be used at various frame rates, the ones currently of interest being 24, 25, and 30 frames per second.