The WBS codes built into Project are simple outline codes with a number for each level in the outline hierarchy. For instance, a WBS code of 2.1.3 might represent the second phase of the project, the first summary task in that phase, and the third work package for that summary task. If your organization uses customized codes, you can build a tailored numbering system—called a code mask—to specify each level of your WBS code. If you use abbreviations for phases, numbers for summary tasks, and letters for work packages, a customized WBS for the design phase of a project might look like this: Dsn 1.a.
Choose Project → WBS → Define Code.
The WBS Code Definition dialog box appears. Although any existing WBS codes show numbers for each level with a period as a separator, the boxes in the WBS Code Definition dialog box are empty until you specify a custom scheme for your WBS codes.
If you assemble several projects into a single master project (Creating a Master Project), you can make WBS codes unique for each project, even if they use the same code mask. If you work with multiple projects, set up the code mask for a new project before you get too deep into defining the project tasks. That way you don't have to renumber all your tasks later. In the Project Code Prefix box, type a prefix for the current project. Project inserts the project prefix at the beginning of the WBS codes for the tasks in the project; for instance, PRJ01.1.4.1.
In the "Code mask" section, in the first Sequence cell, choose the type of characters you want to use for the top level of the hierarchy, as shown in the top figure of Figure 4-7.
You can choose from Numbers (ordered), Uppercase Letters (ordered), Lowercase Letters (ordered), and, for most flexible coding, Characters (unordered). Ordered numbers and letters mean that Project automatically increments the numbers or letters as you add tasks to the WBS, for example, proceeding from 1.1 to 1.2. to 1.3.
Project initially selects Any, which means the entry for the level can be of any length. If the level uses a number, Project increments the number beginning at 1 and continuing to 10, 100, or 1000, if necessary. If the level uses letters, then you can type a code of any number of characters at that level.
Choosing a number limits the entry to between one character and the length you specify. If you limit a numeric entry to one character, Project cycles through the numbers 1 through 9, moves to 0, and then repeats.
In the Separator cell, choose the character that separates the top level from the next level.
Repeat steps 2, 3, and 4 for each additional level of the code mask.
You can specify dozens of levels in a code mask (in fact, a WBS code can be as long as 255 characters), but being miserly with levels makes the schedule easier to comprehend.
Figure 4-7. Top: The choices for characters, length, and separators are limited. If you use unordered characters, you have to type the characters you want for each code, such as Dsn-.1, Const.3, or Rvw.7.Bottom: As you specify the code mask for each level, the "Code preview" box at the top of the dialog box displays a sample WBS code.
After you've defined all the levels in the code mask, be sure that the "Generate WBS code for new task" checkbox is turned on if you want Project to automatically assign a WBS code to new tasks you create.
The only time you might decide to turn this checkbox off is when you plan to renumber all the WBS codes after you've organized your tasks, and don't want to be distracted by the interim codes that Project assigns.
To ensure that your WBS codes are unique, keep the "Verify uniqueness of new WBS codes" checkbox turned on. Click OK, and then review the refreshed WBS codes in the task list, as shown in Figure 4-8.
Although Project adds WBS codes to tasks when the "Generate WBS code for new task" checkbox is turned on, sometimes you want to type WBS codes manually, and that can lead to duplicate WBS codes. The only time you might turn off the "Verify uniqueness of new WBS codes" checkbox is if you're planning to renumber tasks later, and you get tired of the warnings that Project displays. As the box on Documenting a WBS in Another Program explains, you can renumber the WBS codes for tasks to correct or reorder your project.