What is ISO 9642 - Time and control code for 24, 25, and 30 frames per second motion-picture film systems about?  
 ISO 9642 specifies digital code formats and modulation methods for the motion-picture film to be used for timing, control, editing, and synchronization purposes. ISO 9642 also specifies the relationship of the codes to the motion picture frame. 
The modulation method in ISO 9642 is such that a transition occurs at the beginning of every bit period. "One" is represented by a second transition half a bit period after the start of the bit. "Zero" is represented when there is no transition within the bit period.
Who is ISO 9642 - Time and control code for 24, 25, and 30 frames per second motion-picture film systems for? 
 ISO 9642 on motion-picture film systems is useful for: 
- Cinematographers
- Photographers
- Cameramen
- Film industry personnel’s
Why should you use ISO 9642 - Time and control code for 24, 25, and 30 frames per second motion-picture film systems?  
Two types of code are described in ISO 9642. The first type, Type C, is a continuous code that is very similar to the continuous code specified in BS IEC 60461. 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 8, is a non-continuous, block-type code, composed of blocks of data, each complete in itself, with gaps between the blocks. It is designed so that the code can 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.
ISO 9642 specifies requirements for the manufacturer of motion-picture film systems to choose for the materials and production method which ensures the right designing of the optic systems.
