The graphic below illustrates the relationship between a process data calculation formula and the message category.

The following information is contained in the process instruction:

• A message of category NREAD is to be created for the process instruction.

• The order number and phase as well as the source or description of the calculated value (PPPI_SOURCE) are available in the process order. For this reason, the value has already been assigned to the corresponding message characteristics in the process instruction.

• Automatic value assignment in the PI sheet is defined for the date and time.

• The material quantity is to be calculated in the PI sheet. It equals the sum of the material quantities that are transferred from the preceding process instruction using variables MAT1 and MAT2.
  The text Total qty: is to be displayed before the calculated value.

• A value has already been assigned to the message characteristic for the unit of measurement in the process instruction. As the characteristic is assigned after the input value it is displayed after the input field in the PI sheet.

• All other characteristics of the message category are not required for message processing. For this, they have not been included in the process instruction.