When you create a sales document using assembly processing, the system automatically creates a project. The project number contains the sales document number.

In assembly processing, the sales document is linked to a standard network which in turn is assigned to a standard work breakdown structure. When you save the sales document, the system creates an operative project in the background by copying from the predefined standard structures.

Since the WBS element number always has to be unique, the system uses a search and replace technique which takes the first WBS element at level one and uses its number as the basis for creating the number of all other WBS elements in the new project.

If you work with a single structure in the operative structure, the sales document number is used to generate WBS element numbers. How the system determines the project number from the ten-character sales document number, depends on whether you specified project number editing in Customizing of the Project System. SAP recommends that you use project number editing if you are going to be replacing the project number with the sales document number.

In the case of an operative project with several sub-trees, as well as the sales document number, the sales item number is also used, so that the WBS elements in the different sub-trees have different numbers.

The area between the first and the second special character in the number of the standard WBS is replaced by the corresponding number of positions from the sales document number, starting from the right-hand side of the sales document number. The existing spaces are filled from right to left starting with the last digit in the sales document. If there are not enough spaces available, the sales document number is shortened by the first digits. To ensure agreement between the project and sales document, the area between the first and second special character of the number should always be at least ten characters long.

If several sub-trees are to be generated for a project, the area between the second and third special characters in the standard WBS number is replaced by the relevant item number of the sales document number.

When the sales document number is longer than the project number, the system replaces the entire standard WBS number with part of the sales document number, starting from the right of the sales document number. The length of the standard WBS number remains the same.

The system replace the first ten characters of the standard WBS number with the sales document number. Any remaining characters from the original standard WBS number are tacked on to the end of the new project number.