A process data request for a PI sheet must contain the following message characteristics:

• All required characteristics of the requested message category

• All optional characteristics which are to be included in the message

The definition of the message characteristics directly follows the corresponding message category in the data request.

How you need to assign the message characteristics to the data request depends on the way in which they are to be processed, that is, whether their values are to be assigned

• In planning

• Automatically in the PI sheet

• Manually in the PI sheet

• Using a variable defined in the PI sheet

You can define the message characteristics in any sequence. However, the process instruction characteristics pertaining to a message characteristic must be defined in the sequence described in the corresponding section below.

• A process data request can only contain either message characteristics whose value is assigned manually in the PI sheet, or message characteristics to which the value of a variable is assigned.

• If a process data request does not contain message characteristics whose values are to be assigned manually, the data request is not displayed in the PI sheet. The message for the "hidden" data request is created and sent automatically when you send the message for the preceding data request or process data calculation formula.

The process data request comprises the following functions: