Guidelines for Creating and Maintaining a WBS Dictionary

Guidelines for Creating and Maintaining a WBS Dictionary

Last updated on 14th Oct 2020, Artciles, Blog

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The Work Breakdown Structure (WBS) defines a project’s work in terms of deliverables and the process phases appropriate to the organization and/or project. It also is the basis for establishing all steps/tasks, effort, costs and responsibility.

The WBS can be compared to a building’s foundation. Without a good foundation, a building may collapse. Likewise, without a good WBS, project success may be negligible.

The problem with a WBS is that deliverable elements are usually defined with very short descriptions. (In fact the graphical nature of the WBS actually encourages brevity.) This brevity often leads to confusion, miscommunication, and unclear expectations for various stakeholders.

By linking each WBS element to a dictionary-like item that contains descriptive text, the problem can be eliminated. If we extend that concept just a little further by adding several descriptive fields driven by an electronic database system, an extremely beneficial tool can be created.

This tool not only addresses the brevity problem, but also can significantly enhance communication and project control.

Although this topic is being addressed in the PM Advanced Track, it should not be concluded that only large or complex projects could benefit from the use of a WBS Dictionary. Any size or type of project could benefit from this tool.

The concept of a WBS Dictionary is not new, yet almost nothing is written on the topic. The topic will be approached by first discussing the just released work of the PMI Standards Committee on the WBS.

Then various definitions of the WBS Dictionary will be examined. Finally an Extended WBS Dictionary, that utilizes database system concepts and several descriptive fields, will be discussed.

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WBS Dictionary Definitions

  • As previously stated not much has been written on the WBS Dictionary. My research has found a few definitions though:
  • A document that describes each WBS element, including scope, deliverable(s), specification, schedule, resource requirements, and so on.
  • It describes what is in each WBS element, and it may also say what is not in an element, if that is unclear. Example: WBS Element 1.24—Work Environment Request Process—This element describes all the processes that a contract employee will need to use to work effectively on a customers site. Examples include how to get desk space, a telephone, a computer system, access to the Internet, a parking permit.
  • A dictionary consists of an element index and element descriptions. The elements are defined in terms of technical content, including the relationship with other elements, and a work statement describing the functional services required. Source: US Oak Ridge National Laboratory, Project Managers Handbook, Volume 1, Chapter 10.
  • A document that describes each element in the WBS including a Statement of Work (SOW), describing the work content of the WBS element, and a Basis of Estimate (BOE), describing how the budget of the element was developed. Additional information about each WBS element might include the responsible organization contract number, and so on.
  • The WBS Dictionary will often result in the project or contract statement of work (SOW). Source: “R. Max Wideman Comparative Glossary of Project Management Terms v2.0”
  • It lists and defines WBS elements. The dictionary shows the hierarchical relationship of the WBS elements and required resources and processes to produce this element. Each page should include the following information: WBS title; element number; revision number, authorization and description of changes; element task description;
  • specification number and title; contract line item; contract end item and quantity; cost content and description; and contractor and subcontractor names.
  • Initially, the Government program manager prepares the dictionary, and the contractor later revises it as the CWBS (Contract WBS) is developed.
  • It is updated periodically to include changes and reflect the current program status. Source: US Air Force Material Command, Financial Management Reference System, Chapter 10—Work Breakdown Structure.
  • The Work Breakdown Structure Dictionary is a useful resource for project management, and should be consulted for relevant information on each component of the work breakdown structure (WBS).
  • The WBS dictionary includes entries for each WBS component that briefly defines the scope or statement of the work, defines deliverables, contains a list of associated activities, and provides a list of recognized milestones to gage progress.

WBS Dictionary Example: How to Create a Work Breakdown Structure Dictionary


How Does It Function as a Project Management Tool?

A WBS Dictionary is merely a supporting document, which provides the definitions for each component contained in the Work Breakdown Structure.

This type of dictionary is often recommended as a reference resource material for task-oriented projects comprising several work phases. Its origins stem from US Military Defense projects; hence its functionality and effectiveness as a supplementary tool have been largely proven for broad-based and extensive projects.

The process involved in developing this project management tool is nothing complex. It is a purely mental activity of describing the functions to be fulfilled for each task by using proper labels and numeric indices. Its main objective is to furnish every team member with clear task-descriptions as a means to eliminate confusion. As a dictionary, it defines the tasks, the requirements, and the deliverables all in accordance with the function’s relevance to the overall objectives of the project.

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Providing a Sample of a Work Breakdown Structure

Since a WBS Dictionary accompanies a Work Breakdown Structure, the latter is provided with an image which readers can reference as we proceed with the explanations. Take note, however, that the example provided is only a WBS for Phase 1 of a business development project and is not the entire representation of the project management tool.

The structure is graphically presented by using a tree chart showing a subdivision of tasks that are required to complete Phase 1 of a particular undertaking. The entire project is broken down into successive subcomponents considered as manageable subdivisions based on size, duration and responsibility.


The Work Breakdown Structure Dictionary

Now take a look at the contents of the image on your left, which is the dictionary that accompanies the WBS sample above.

This is usually prepared for large and complex projects that have many tasks and is prepared by the project manager in coordination with the team members, who will contribute by providing work-related inputs.

Both the project manager and the team members should furnish a collective description of each task, which will serve as a set of clear definitions about each assigned activity and project requirement as they are linked to all underlying functions.

The document is useful for maintaining a clear line of communication, since team members would know the owners of a particular project function.

A closer look at this sample will show that each major function is provided with numerical indices that matches each function under each type of functional category. In this example, the WBS is described as Phase 1 while the first major function is stated as Project Management – Project Manager. This particular component was then assigned with the numeric code 1.1. and is owned by the Project Manager. Henceforth, all dictionary entries should have a matching definition for each of these numeric codes.

Where other workplace environments make use of the officers’ and staff’s initials to identify a related function or concern during meetings, planning and deliberations — the identifying numeric codes may also be used as a form of identification. It is possible for complex and large-scale undertakings to experience turnovers while the project is still incomplete or ongoing; hence, using numeric codes as alternative, dispenses with the need for name recalling.

Although structures and manners of presentations may vary, this project management tool serves as a point of reference for other task-related information, which generally includes the following:

  • An identifier or label for each individual task
  • Description
  • Job owner
  • Objectives
  • Functional requirements to be fulfilled
  • Technical requirements for completing the task
  • End objective
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Each component should end with a statement about the function’s main objective.

WBS Dictionary Template

1WBS CodeEnter the WBS Title and identify it as a Work Package, Planning and/or Control Account.
2Responsible Organization/ IndividualName the single organization, group or individual that has been assigned sole responsibility for making sure the Work Package is completed. Include contact information.
3DescriptionDefine Work Package boundaries. Frame the scope content so that it is clear what scope is included and excluded. If it is a Planning Package, describe the known and unknown scope.
4DeliverablesIdentify the product, service or results created when all of the work in this Work Package is complete. Include any critical intermediate deliverables.
5Acceptance CriteriaDescribe the functional and physical requirements in order to meet customer expectations and quality requirements. Include any unique approvals required for acceptance.
6BudgetDesignate the budget for this Work Package, plus any critical resource information and assumptions.
7MilestonesList any Start Dates, End Dates, Intermediate Milestones, Interdependencies, Constraints and any assumption for the deliverables.
8RisksInclude any known threats and opportunities with response strategies.
9Additional InformationDescribe any additional information, such as references, related work packages, etc.
10Approvals:                Date:Rev:

The WBS Dictionary is the formal project document that provides detailed descriptions of key information for all Elements in the Work Breakdown Structure and must comply with the 100% Rule. The 100% Rule requires that the WBS captures 100% of the project scope. However, since the titles of the WBS Elements are only one or two words, it is impossible to confirm by just using the WBS that this rule has been met. The WBS Dictionary is the project document that describes the work in each Element such that the project team is able to plan and execute 100% of the scope.

Many references describe the WBS Dictionary as a Work Packages description tool. The Work Packages are defined as the lowest Elements in each Leg of the WBS. While this statement is true, the WBS Dictionary actually describes every Element in the WBS. The WBS Dictionary is created in a hierarchical format just like the Work Breakdown Structure. The Level 1 Element descriptions must be created first to understand its boundaries and ensure alignment with the lower level Elements. This is the best way to ensure that the 100% Rule is being followed.

How to Create a WBS Dictionary

After the Work Breakdown Structure has been approved, the WBS Dictionary can be created. The creation of the WBS Dictionary is led by the Project Manager and developed by project team members who are Subject Matter Experts (SME). The development approach begins with the Level 1 Elements, proceeds down each Leg and terminates with the Work Packages. This hierarchical approach ensures that the work within each Level 1 remains in alignment and compliance with the 100% Rule.

When creating the WBS Dictionary, it is important to keep the content of each Element brief. The primary purpose of the WBS Dictionary is for project team members to have a clear understanding of the work being performed in all the Elements and particularly the Work Packages. It is not a rewrite of the Scope Statement, a Work Authorization Package, a Contract or Agreement, etc. It is a concise explanation of important topics related to each Element. A good way to ensure this format is followed is to use a WBS Dictionary template while following these steps:

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    Assemble the project team SMEs and review the Work Breakdown Structure to validate the 100% Rule. Ensure everyone understands the WBS logic and assumptions. Revise the WBS based on feedback from the SMEs.
    Using a template with the following minimum topics, create the content for each of the Level 1 WBS Elements (See Figure 1):
    1. 1. WBS Level 1 ID Code and Title – Identify it as a Control Account if it is one.
    2. 2. Description – Define the Element boundaries and frame the scope content so that it is clear what scope is included and excluded.
    3. 3. Primary Deliverable(s) – The product, service or result created when all of the work in this WBS Leg is complete.
    4. 4. Acceptance Criteria – Functional and physical requirements that meet customer expectations.
    5. 5. Summary Budget – Budget for the entire WBS Leg, plus assumptions.
    6. 6. Milestones – Milestone for the Primary Deliverable(s). Also include any assumptions, constraints, and schedule interdependencies with other Primary Deliverables in the other WBS Level 1 Elements
    7. 7. Key Risks – Include any key threats and opportunities with response strategies.
    Return to the Work Breakdown Structure and check if the Level 1 Elements should be revised based on the newly created content from the WBS Dictionary. Confirm that the Level 1 Elements capture 100% of the scope.
    Continue creating similar content using the same template for the remaining Elements down to, but not including the Work Packages. Adjust the content to reflect the respective Level of the Element; i.e., Level 2, 3, etc.
    Using a template with the following minimum topics, create the content for each of the Work Package Elements:
    1. 1. WBS Level 1 ID Code and Title – Identify it as a Control Account if it is one.
    2. 2. Responsible Organization/Individual – This is the single organization, group or individual that has been assigned sole responsibility for making sure the Work Package is completed.
    3. 3. Description – Define Work Package boundaries. Frame the scope content so that it is clear what scope is included and excluded. If it is a Planning Package, describe the known and unknown scope.
    4. 4. Deliverables – The product, service or results created when all of the work in this Work Package is complete. Include any critical intermediate deliverables.
    5. 5. Acceptance Criteria – Functional and physical requirements that meet customer expectations. Include any unique approvals required for acceptance.
    6. 6. Budget – Budget for this Work Package, plus any critical resource information and assumptions.
    7. 7. Milestones – Start Date, End Date, Intermediate Milestones, Interdependencies, Constraints and any assumptions.
    8. 8. Risks – Include any known threats and opportunities with response strategies.
  6. 6. VALIDATE 100% RULE:
    Validate that the Dictionary adequately captures the scope required to produce the deliverable. Ensure that the WBS Dictionary reflects 100% of the scope.


How to Use a WBS Dictionary

Just like the Work Breakdown Structure, the WBS Dictionary is a critical scope planning tool. It also serves as a basis for preparing work authorization documents, schedules, cost estimates and monitoring and controlling baselines. As mentioned many times in this article, it defines the work in the Work Breakdown Structure. It contains minimal essential information to understand the project requirements and meet all of the deliverables’ acceptance criteria. Combined with the approved scope statement and the Work Breakdown Structure, the WBS dictionary is the third and final component of the scope baseline. The baseline is the project document used to measure project performance. The scope baseline is the formal plan that is compared against actual results for monitoring and controlling scope execution.

Work authorization documents are prepared based on the Work Package information and used to execute work. The Work Package information in the WBS Dictionary provides the basic data required for the creation work authorization documents so that the deliverables meet the acceptance criteria and can be transferred to the customer. The Project Team should refer to the WBS Dictionary throughout project execution to ensure the deliverables meet requirements.

The WBS Dictionary is also the primary input for creating and monitoring schedule activities and cost estimates. Decomposing Work Packages create activities (See Figure 2). These activities become the activities that build a schedule using a Gantt chart format (See Figure 3). Once the activities have been resource-loaded, cost estimates can be created at the activity level, then aggregated via the Work Breakdown Structure throughout the entire project. This easily permits the project to monitor and control costs at any element in the WBS; a Work Package or Control Account.



Gantt-Chart, work package activities, wbs dictionary


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