By creating process instructions in the master recipe and the process order, you specify information that is relevant to process control. For example, in a process instruction, you can specify a temperature value to be set at a thermostat or you can request a message reporting the material quantity consumed in a process step.

Process instructions can have different functions depending on the type of information they convey. For example, some process instructions pass parameters to process control whereas others trigger the sending of a process message. For this reason, process instructions are subdivided into several types according to their functions. The type of a process instruction determines how the instruction is processed.

You define the contents of a process instruction by assigning characteristics (for example, material number or quantity) and characteristic values to it. You can thus adjust your process instructions to the specific requirements of your processes and the control systems involved.

To standardize and simplify the editing of process instructions, you use process instruction categories whose type and characteristic structure are defined in Customizing. In the R/3 System, a process instruction can only be created with reference to a process instruction category.

The process instruction type and the characteristic structure you use for your process instructions depends not only on the information you want to convey but also on the destination. For example, the information required by a control system is different to that required by a process operator. Moreover, different control systems usually require different process instructions according to their functionality.