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INTRODUCTION

1.1 OVERVIEW AND PURPOSE OF THIS GUIDE

Project management is not new. It has been in use for hundreds of years. Examples of project outcomes include:

The outcomes of these projects were the result of leaders and managers applying project management practices, principles, processes, tools, and techniques to their work. The managers of these projects used a set of key skills and applied knowledge to satisfy their customers and other people involved in and affected by the project. By the mid-20th century, project managers began the work of seeking recognition for project management as a profession. One aspect of this work involved obtaining agreement on the content of the body of knowledge (BOK) called project management. This BOK became known as the Project Management Body of Knowledge (PMBOK). The Project Management Institute (PMI) produced a baseline of charts and glossaries for the PMBOK. Project managers soon realized that no single book could contain the entire PMBOK. Therefore, PMI developed and published A Guide to the Project Management Body of Knowledge (PMBOK® Guide).

PMI defines the project management body of knowledge (PMBOK) as a term that describes the knowledge within the profession of project management. The project management body of knowledge includes proven traditional practices that are widely applied as well as innovative practices that are emerging in the profession.

The body of knowledge (BOK) includes both published and unpublished materials. This body of knowledge is constantly evolving. This PMBOK® Guide identifies a subset of the project management body of knowledge that is generally recognized as good practice.

The project manager works with the project team and other stakeholders to determine and use the appropriate generally recognized good practices for each project. Determining the appropriate combination of processes, inputs, tools, techniques, outputs and life cycle phases to manage a project is referred to as “tailoring” the application of the knowledge described in this guide.

This PMBOK® Guide is different from a methodology. A methodology is a system of practices, techniques, procedures, and rules used by those who work in a discipline. This PMBOK® Guide is a foundation upon which organizations can build methodologies, policies, procedures, rules, tools and techniques, and life cycle phases needed to practice project management.

1.1.1 THE STANDARD FOR PROJECT MANAGEMENT

This guide is based on The Standard for Project Management [1]. A standard is a document established by an authority, custom, or general consent as a model or example. As an American National Standards Institute (ANSI) standard, The Standard for Project Management was developed using a process based on the concepts of consensus, openness, due process, and balance. The Standard for Project Management is a foundational reference for PMI's project management professional development programs and the practice of project management. Because project management needs to be tailored to fit the needs of the project, the standard and the guide are both based on descriptive practices, rather than prescriptive practices. Therefore, the standard identifies the processes that are considered good practices on most projects, most of the time. The standard also identifies the inputs and outputs that are usually associated with those processes. The standard does not require that any particular process or practice be performed. The Standard for Project Management is included as Part II of A Guide to the Project Management Body of Knowledge (PMBOK® Guide).

The PMBOK® Guide provides more detail about key concepts, emerging trends, considerations for tailoring the project management processes, and information on how tools and techniques are applied to projects. Project managers may use one or more methodologies to implement the project management processes outlined in the standard.

The scope of this guide is limited to the discipline of project management, rather than the full spectrum of portfolios, programs, and projects. Portfolios and programs will be addressed only to the degree they interact with projects. PMI publishes two other standards that address the management of portfolios and programs:

1.1.2 COMMON VOCABULARY

A common vocabulary is an essential element of a professional discipline. The PMI Lexicon of Project Management Terms [4] provides the foundational professional vocabulary that can be consistently used by organizations, portfolio, program, and project managers and other project stakeholders. The Lexicon will continue to evolve over time. The glossary to this guide includes the vocabulary in the Lexicon along with additional definitions. There may be other industry-specific terms used in projects that are defined by that industry's literature.

1.1.3 CODE OF ETHICS AND PROFESSIONAL CONDUCT

PMI publishes the Code of Ethics and Professional Conduct [5] to instill confidence in the project management profession and to help an individual in making wise decisions, particularly when faced with difficult situations where the individual may be asked to compromise his or her integrity or values. The values that the global project management community defined as most important were responsibility, respect, fairness, and honesty. The Code of Ethics and Professional Conduct affirms these four values as its foundation.

The Code of Ethics and Professional Conduct includes both aspirational standards and mandatory standards. The aspirational standards describe the conduct that practitioners, who are also PMI members, certification holders, or volunteers, strive to uphold. Although adherence to the aspirational standards is not easily measured, conduct in accordance with these is an expectation for those who consider themselves to be professionals—it is not optional. The mandatory standards establish firm requirements and, in some cases, limit or prohibit practitioner behavior. Practitioners who are also PMI members, certification holders, or volunteers and who do not conduct themselves in accordance with these standards will be subject to disciplinary procedures before PMI's Ethics Review Committee.

1.2 FOUNDATIONAL ELEMENTS

This section describes foundational elements necessary for working in and understanding the discipline of project management.

1.2.1 PROJECTS

A project is a temporary endeavor undertaken to create a unique product, service, or result.

Fulfillment of project objectives may produce one or more of the following deliverables:

Repetitive elements may be present in some project deliverables and activities. This repetition does not change the fundamental and unique characteristics of the project work. For example, office buildings can be constructed with the same or similar materials and by the same or different teams. However, each building project remains unique in key characteristics (e.g., location, design, environment, situation, people involved).

Projects are undertaken at all organizational levels. A project can involve a single individual or a group. A project can involve a single organizational unit or multiple organizational units from multiple organizations.

Examples of projects include but are not limited to:

Projects are temporary, but their deliverables may exist beyond the end of the project. Projects may produce deliverables of a social, economic, material, or environmental nature. For example, a project to build a national monument will create a deliverable expected to last for centuries.

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Business value in projects refers to the benefit that the results of a specific project provide to its stakeholders. The benefit from projects may be tangible, intangible, or both.

Examples of tangible elements include:

Examples of intangible elements include:

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These factors influence an organization's ongoing operations and business strategies. Leaders respond to these factors in order to keep the organization viable. Projects provide the means for organizations to successfully make the changes necessary to deal with these factors. These factors ultimately should link to the strategic objectives of the organization and the business value of each project.

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1.2.2 THE IMPORTANCE OF PROJECT MANAGEMENT

Project management is the application of knowledge, skills, tools, and techniques to project activities to meet the project requirements. Project management is accomplished through the appropriate application and integration of the project management processes identified for the project. Project management enables organizations to execute projects effectively and efficiently.

Effective project management helps individuals, groups, and public and private organizations to:

Poorly managed projects or the absence of project management may result in:

Projects are a key way to create value and benefits in organizations. In today's business environment, organizational leaders need to be able to manage with tighter budgets, shorter timelines, scarcity of resources, and rapidly changing technology. The business environment is dynamic with an accelerating rate of change. To remain competitive in the world economy, companies are embracing project management to consistently deliver business value.

Effective and efficient project management should be considered a strategic competency within organizations. It enables organizations to:

1.2.3 RELATIONSHIP OF PROJECT, PROGRAM, PORTFOLIO, AND OPERATIONS MANAGEMENT

1.2.3.1 OVERVIEW

Using project management processes, tools, and techniques puts in place a sound foundation for organizations to achieve their goals and objectives. A project may be managed in three separate scenarios: as a stand-alone project (outside of a portfolio or program), within a program, or within a portfolio. Project managers interact with portfolio and program managers when a project is within a program or portfolio. For example, multiple projects may be needed to accomplish a set of goals and objectives for an organization. In those situations, projects may be grouped together into a program. A program is defined as a group of related projects, subsidiary programs, and program activities managed in a coordinated manner to obtain benefits not available from managing them individually. Programs are not large projects. A very large project may be referred to as a megaproject. As a guideline, megaprojects cost US$1billion or more, affect 1 million or more people, and run for years.

Some organizations may employ the use of a project portfolio to effectively manage multiple programs and projects that are underway at any given time. A portfolio is defined as projects, programs, subsidiary portfolios, and operations managed as a group to achieve strategic objectives. Figure 1-3 illustrates an example of how portfolios, programs, projects, and operations are related in a specific situation.

Program management and portfolio management differ from project management in their life cycles, activities, objectives, focus, and benefits. However, portfolios, programs, projects, and operations often engage with the same stakeholders and may need to use the same resources (see Figure 1-3), which may result in a conflict in the organization. This type of a situation increases the need for coordination within the organization through the use of portfolio, program, and project management to achieve a workable balance in the organization.

Figure 1-3 illustrates a sample portfolio structure indicating relationships between the programs, projects, shared resources, and stakeholders. The portfolio components are grouped together in order to facilitate the effective governance and management of the work that helps to achieve organizational strategies and priorities. Organizational and portfolio planning impact the components by means of prioritization based on risk, funding, and other considerations. The portfolio view allows organizations to see how the strategic goals are reflected in the portfolio. This portfolio view also enables the implementation and coordination of appropriate portfolio, program, and project governance. This coordinated governance allows authorized allocation of human, financial, and physical resources based on expected performance and benefits.

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Looking at project, program, and portfolio management from an organizational perspective:

Table 1-2 gives a comparative overview of portfolios, programs, and projects.

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1.2.3.2 PROGRAM MANAGEMENT

Program management is defined as the application of knowledge, skills, and principles to a program to achieve the program objectives and to obtain benefits and control not available by managing program components individually. A program component refers to projects and other programs within a program. Project management focuses on interdependencies within a project to determine the optimal approach for managing the project. Program management focuses on the interdependencies between projects and between projects and the program level to determine the optimal approach for managing them. Actions related to these program and project-level interdependencies may include:

An example of a program is a new communications satellite system with projects for the design and construction of the satellite and the ground stations, the launch of the satellite, and the integration of the system.

For more information on program management, see The Standard for Program Management [3].

1.2.3.3 PORTFOLIO MANAGEMENT

A portfolio is defined as projects, programs, subsidiary portfolios, and operations managed as a group to achieve strategic objectives.

Portfolio management is defined as the centralized management of one or more portfolios to achieve strategic objectives. The programs or projects of the portfolio may not necessarily be interdependent or directly related.

The aim of portfolio management is to:

Portfolio management also confirms that the portfolio is consistent with and aligned with organizational strategies.

Maximizing the value of the portfolio requires careful examination of the components that comprise the portfolio. Components are prioritized so that those contributing the most to the organization's strategic objectives have the required financial, team, and physical resources.

For example, an infrastructure organization that has the strategic objective of maximizing the return on its investments may put together a portfolio that includes a mix of projects in oil and gas, power, water, roads, rail, and airports. From this mix, the organization may choose to manage related projects as one portfolio. All of the power projects may be grouped together as a power portfolio. Similarly, all of the water projects may be grouped together as a water portfolio. However, when the organization has projects in designing and constructing a power plant and then operates the power plant to generate energy, those related projects can be grouped in one program. Thus, the power program and similar water program become integral components of the portfolio of the infrastructure organization.

For more information on portfolio management, see The Standard for Portfolio Management [2].

1.2.3.4 OPERATIONS MANAGEMENT

Operations management is an area that is outside the scope of formal project management as described in this guide.

Operations management is concerned with the ongoing production of goods and/or services. It ensures that business operations continue efficiently by using the optimal resources needed to meet customer demands. It is concerned with managing processes that transform inputs (e.g., materials, components, energy, and labor) into outputs (e.g., products, goods, and/or services).

1.2.3.5 OPERATIONS AND PROJECT MANAGEMENT

Changes in business or organizational operations may be the focus of a project—especially when there are substantial changes to business operations as a result of a new product or service delivery. Ongoing operations are outside of the scope of a project; however, there are intersecting points where the two areas cross.

Projects can intersect with operations at various points during the product life cycle, such as;

At each point, deliverables and knowledge are transferred between the project and operations for implementation of the delivered work. This implementation occurs through a transfer of project resources or knowledge to operations or through a transfer of operational resources to the project.

1.2.3.6 ORGANIZATIONAL PROJECT MANAGEMENT (OPM) AND STRATEGIES

Portfolios, programs, and projects are aligned with or driven by organizational strategies and differ in the way each contributes to the achievement of strategic goals:

Within portfolios or programs, projects are a means of achieving organizational goals and objectives. This is often accomplished in the context of a strategic plan that is the primary factor guiding investments in projects. Alignment with the organization's strategic business goals can be achieved through the systematic management of portfolios, programs, and projects through the application of organizational project management (OPM). OPM is defined as a framework in which portfolio, program, and project management are integrated with organizational enablers in order to achieve strategic objectives.

The purpose of OPM is to ensure that the organization undertakes the right projects and allocates critical resources appropriately. OPM also helps to ensure that all levels in the organization understand the strategic vision, the initiatives that support the vision, the objectives, and the deliverables. Figure 1-4 shows the organizational environment where strategy, portfolio, programs, projects, and operations interact.

For more information on OPM, refer to Implementing Organizational Project Management: A Practice Guide [8].

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1.2.4 COMPONENTS OF THE GUIDE

Projects comprise several key components that, when effectively managed, result in their successful completion. This guide identifies and explains these components. The various components interrelate to one another during the management of a project.

The key components are described briefly in Table 1-3. These components are more fully explained in the sections that follow the table.

Table 1-3. Description of PMBOK® Guide Key Components

PMBOK® Guide Key Component Brief Description
Project life cycle (Section 1.2.4.1) The series of phases that a project passes through from its start to its completion.
Project phase (Section 1.2.4.2) A collection of logically related project activities that culminates in the completion of one or more deliverables.
Phase gate (Section 1.2.4.3) A review at the end of a phase in which a decision is made to continue to the next phase, to continue with modification, or to end a program or project.
Project management processes (Section 1.2.4.4) A systematic series of activities directed toward causing an end result where one or more inputs will be acted upon to create one or more outputs.
Project Management Process Group (Section 1.2.4.5) A logical grouping of project management inputs, tools and techniques, and outputs. The Project Management Process Groups include Initiating, Planning, Executing, Monitoring and Controlling, and Closing. Project Management Process Groups are not project phases.
Project Management Knowledge Area (Section 1.2.4.6) An identified area of project management defined by its knowledge requirements and described in terms of its component processes, practices, inputs, outputs, tools, and techniques.

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1.2.4.1 PROJECT AND DEVELOPMENT LIFE CYCLES

A project life cycle is the series of phases that a project passes through from its start to its completion. It provides the basic framework for managing the project. This basic framework applies regardless of the specific project work involved. The phases may be sequential, iterative, or overlapping. All projects can be mapped to the generic life cycle shown in Figure 1-5.

Project life cycles can be predictive or adaptive. Within a project life cycle, there are generally one or more phases that are associated with the development of the product, service, or result. These are called a development life cycle. Development life cycles can be predictive, iterative, incremental, adaptive, or a hybrid model:

It is up to the project management team to determine the best life cycle for each project. The project life cycle needs to be flexible enough to deal with the variety of factors included in the project. Life cycle flexibility may be accomplished by:

Project life cycles are independent of product life cycles, which may be produced by a project. A product life cycle is the series of phases that represent the evolution of a product, from concept through delivery, growth, maturity, and to retirement.

1.2.4.2 PROJECT PHASE

A project phase is a collection of logically related project activities that culminates in the completion of one or more deliverables. The phases in a life cycle can be described by a variety of attributes. Attributes may be measurable and unique to a specific phase. Attributes may include but are not limited to:

Projects may be separated into distinct phases or subcomponents. These phases or subcomponents are generally given names that indicate the type of work done in that phase. Examples of phase names include but are not limited to:

The project phases may be established based on various factors including, but not limited to:

Using multiple phases may provide better insight to managing the project. It also provides an opportunity to assess the project performance and take necessary corrective or preventive actions in subsequent phases. A key component used with project phases is the phase review (see Section 1.2.4.3).

1.2.4.3 PHASE GATE

A phase gate, is held at the end of a phase. The project's performance and progress are compared to project and business documents including but not limited to:

A decision (e.g., go/no-go decision) is made as a result of this comparison to:

Depending on the organization, industry, or type of work, phase gates may be referred to by other terms such as, phase review, stage gate, kill point, and phase entrance or phase exit. Organizations may use these reviews to examine other pertinent items which are beyond the scope of this guide, such as product-related documents or models.

1.2.4.4 PROJECT MANAGEMENT PROCESSES

The project life cycle is managed by executing a series of project management activities known as project management processes. Every project management process produces one or more outputs from one or more inputs by using appropriate project management tools and techniques. The output can be a deliverable or an outcome. Outcomes are an end result of a process. Project management processes apply globally across industries.

Project management processes are logically linked by the outputs they produce. Processes may contain overlapping activities that occur throughout the project. The output of one process generally results in either:

Figure 1-6 shows an example of how inputs, tools and techniques, and outputs relate to each other within a process, and with other processes.

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The number of process iterations and interactions between processes varies based on the needs of the project. Processes generally fall into one of three categories:

Project management is accomplished through the appropriate application and integration of logically grouped project management processes. While there are different ways of grouping processes, the PMBOK® Guide groups processes into five categories called Process Groups.

1.2.4.5 PROJECT MANAGEMENT PROCESS GROUPS

A Project Management Process Group is a logical grouping of project management processes to achieve specific project objectives. Process Groups are independent of project phases. Project management processes are grouped into the following five Project Management Process Groups:

Process flow diagrams are used throughout this guide. The project management processes are linked by specific inputs and outputs where the result or outcome of one process may become the input to another process that is not necessarily in the same Process Group. Note that Process Groups are not the same as project phases (see Section 1.2.4.2).

1.2.4.6 PROJECT MANAGEMENT KNOWLEDGE AREAS

In addition to Process Groups, processes are also categorized by Knowledge Areas. A Knowledge Area is an identified area of project management defined by its knowledge requirements and described in terms of its component processes, practices, inputs, outputs, tools, and techniques.

Although the Knowledge Areas are interrelated, they are defined separately from the project management perspective. The ten Knowledge Areas identified in this guide are used in most projects most of the time. The ten Knowledge Areas described in this guide are:

The needs of a specific project may require one or more additional Knowledge Areas, for example, construction may require financial management or safety and health management. Table 1-4 maps the Project Management Process Groups and Knowledge Areas. Sections 4 through 13 provide more detail about each Knowledge Area. This table is an overview of the basic processes described in Sections 4 through 13.

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1.2.4.7 PROJECT MANAGEMENT DATA AND INFORMATION

Throughout the life cycle of a project, a significant amount of data is collected, analyzed, and transformed. Project data are collected as a result of various processes and are shared within the project team. The collected data are analyzed in context, aggregated, and transformed to become project information during various processes. Information is communicated verbally or stored and distributed in various formats as reports. See Section 4.3 for more detail on this topic.

Project data are regularly collected and analyzed throughout the project life cycle. The following definitions identify key terminology regarding project data and information:

Figure 1-7 shows the flow of project information across the various processes used in managing the project.

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1.2.5 TAILORING

Usually, project managers apply a project management methodology to their work. A methodology is a system of practices, techniques, procedures, and rules used by those who work in a discipline. This definition makes it clear that this guide itself is not a methodology.

This guide and The Standard for Project Management [1] are recommended references for tailoring, because these standard documents identify the subset of the project management body of knowledge that is generally recognized as good practice. “Good practice” does not mean that the knowledge described should always be applied uniformly to all projects. Specific methodology recommendations are outside the scope of this guide.

Project management methodologies may be:

The appropriate project management processes, inputs, tools, techniques, outputs, and life cycle phases should be selected to manage a project. This selection activity is known as tailoring project management to the project. The project manager collaborates with the project team, sponsor, organizational management, or some combination thereof, in the tailoring. In some cases, the organization may require specific project management methodologies be used.

Tailoring is necessary because each project is unique; not every process, tool, technique, input, or output identified in the PMBOK® Guide is required on every project. Tailoring should address the competing constraints of scope, schedule, cost, resources, quality, and risk. The importance of each constraint is different for each project, and the project manager tailors the approach for managing these constraints based on the project environment, organizational culture, stakeholder needs, and other variables.

In tailoring project management, the project manager should also consider the varying levels of governance that may be required and within which the project will operate, as well as considering the culture of the organization. In addition, consideration of whether the customer of the project is internal or external to the organization may affect project management tailoring decisions.

Sound project management methodologies take into account the unique nature of projects and allow tailoring, to some extent, by the project manager. However, the tailoring that is included in the methodology may still require additional tailoring for a given project.

1.2.6 PROJECT MANAGEMENT BUSINESS DOCUMENTS

The project manager needs to ensure that the project management approach captures the intent of business documents. These documents are defined in Table 1-5. These two documents are interdependent and iteratively developed and maintained throughout the life cycle of the project.

Table 1-5. Project Business Documents

Project Business Documents Definition
Project business case A documented economic feasibility study used to establish the validity of the benefits of a selected component lacking sufficient definition and that is used as a basis for the authorization of further project management activities.
Project benefits management plan The documented explanation defining the processes for creating, maximizing, and sustaining the benefits provided by a project.

The project sponsor is generally accountable for the development and maintenance of the project business case document. The project manager is responsible for providing recommendations and oversight to keep the project business case, project management plan, project charter, and project benefits management plan success measures in alignment with one another and with the goals and objectives of the organization.

Project managers should appropriately tailor the noted project management documents for their projects. In some organizations, the business case and benefits management plan are maintained at the program level. Project managers should work with the appropriate program managers to ensure the project management documents are aligned with the program documents. Figure 1-8 illustrates the interrelationship of these critical project management business documents and the needs assessment. Figure 1-8 shows an approximation of the life cycle of these various documents against the project life cycle.

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1.2.6.1 PROJECT BUSINESS CASE

The project business case is a documented economic feasibility study used to establish the validity of the benefits of a selected component lacking sufficient definition and that is used as a basis for the authorization of further project management activities. The business case lists the objectives and reasons for project initiation. It helps measure the project success at the end of the project against the project objectives. The business case is a project business document that is used throughout the project life cycle. The business case may be used before the project initiation and may result in a go/no-go decision for the project.

A needs assessment often precedes the business case. The needs assessment involves understanding business goals and objectives, issues, and opportunities and recommending proposals to address them. The results of the needs assessment may be summarized in the business case document.

The process of defining the business need, analyzing the situation, making recommendations, and defining evaluation criteria is applicable to any organization's projects. A business case may include but is not limited to documenting the following:

Examples of criteria categories used for analysis of a situation are:

The business case document provides the basis to measure success and progress throughout the project life cycle by comparing the results with the objectives and the identified success criteria. See Business Analysis for Practitioners: A Practice Guide [7].

1.2.6.2 PROJECT BENEFITS MANAGEMENT PLAN

The project benefits management plan is the document that describes how and when the benefits of the project will be delivered, and describes the mechanisms that should be in place to measure those benefits. A project benefit is defined as an outcome of actions, behaviors, products, services, or results that provide value to the sponsoring organization as well as to the project's intended beneficiaries. Development of the benefits management plan begins early in the project life cycle with the definition of the target benefits to be realized. The benefits management plan describes key elements of the benefits and may include but is not limited to documenting the following:

Developing the benefits management plan makes use of the data and information documented in the business case and needs assessment. For example, the cost-benefit analyses recorded in the documents illustrate the estimate of costs compared to the value of the benefits realized by the project. The benefits management plan and the project management plan include a description of how the business value resulting from the project becomes part of the organization's ongoing operations, including the metrics to be used. The metrics provide verification of the business value and validation of the project's success.

Development and maintenance of the project benefits management plan is an iterative activity. This document complements the business case, project charter, and project management plan. The project manager works with the sponsor to ensure that the project charter, project management plan, and the benefits management plan remain in alignment throughout the life cycle of the project. See Business Analysis for Practitioners: A Practice Guide [7], The Standard for Program Management [3], and The Standard for Portfolio Management [2].

1.2.6.3 PROJECT CHARTER AND PROJECT MANAGEMENT PLAN

The project charter is defined as a document issued by the project sponsor that formally authorizes the existence of a project and provides the project manager with the authority to apply organizational resources to project activities.

The project management plan is defined as the document that describes how the project will be executed, monitored, and controlled.

See Section 4 on Project Integration Management for more information on the project charter and the project management plan.

1.2.6.4 PROJECT SUCCESS MEASURES

One of the most common challenges in project management is determining whether or not a project is successful.

Traditionally, the project management metrics of time, cost, scope, and quality have been the most important factors in defining the success of a project. More recently, practitioners and scholars have determined that project success should also be measured with consideration toward achievement of the project objectives.

Project stakeholders may have different ideas as to what the successful completion of a project will look like and which factors are the most important. It is critical to clearly document the project objectives and to select objectives that are measurable. Three questions that the key stakeholders and the project manager should answer are:

The answer to these questions should be documented and agreed upon by the key stakeholders and the project manager.

Project success may include additional criteria linked to the organizational strategy and to the delivery of business results. These project objectives may include but are not limited to:

The project team needs to be able to assess the project situation, balance the demands, and maintain proactive communication with stakeholders in order to deliver a successful project.

When the business alignment for a project is constant, the chance for project success greatly increases because the project remains aligned with the strategic direction of the organization.

It is possible for a project to be successful from a scope/schedule/budget viewpoint, and to be unsuccessful from a business viewpoint. This can occur when there is a change in the business needs or the market environment before the project is completed.