U to Z

A pdf of the complete Praxis Comparative Glossary can be downloaded here.


From Uniform distribution to Zero float


Uniform distribution

A distribution used in Monte Carlo analysis to indicate that all durations or costs between the optimistic and pessimistic duration estimates have an equal chance of occurring.

Unlimited schedule

A schedule calculated based upon unlimited availability of resources, i.e. the opposite of a resource limited schedule. Critical path analysis is a form of unlimited schedule because it does not take resource limits into account when scheduling activities.

Update the business case

An activity from the PRINCE2 Managing a Stage Boundary (SB) process.
At a stage boundary in PRINCE2, the forthcoming stage plan is produced and this results in the project plan being updated. The revised plans are then used to update the project’s business case so that a decision can be made whether or not to proceed with the next stage.

In Praxis this is incorporated in the plan next tranche/stage activity in the boundaries process. Since neither PMBoK® guide nor ISO21500 define stages, keeping the business case up to date is an ongoing process.

Update the project plan

An activity from the PRINCE2 Managing a Stage Boundary (SB) process. At each stage boundary the project plan is updated to reflect the final version of the stage plan being concluded and the latest plan for the next stage. This activity will also be triggered by the preparation of an exception plan.

In Praxis, this is covered by the assemble documentation activity in the boundaries process.

Neither ISO21500 nor the PMBoK® guide have a formal approach to stages built into their processes. Such updates should be considered implicit in processes such as Monitor and Control Project Work (PMBoK® guide) and Control project work (ISO21500).

User acceptance

Acceptance by the person or group who will use a deliverable once it has been handed over.

User story

A user story is a type of functional specification used in agile development. It describes a software feature from the perspective of the user experience. It includes a description of the user, what they want and why.


The group of people who are intended to benefit from, or operate the products of, the project. The users are key stakeholders in the project.

PRINCE2 nominates a senior user who sits on the project board to provide sponsorship.

V life cycle

A life cycle model, drawn in the form of a ‘V’, which demonstrates the relationship between earlier and later phases of the life cycle.

Validate Scope (5.5)

The PMBoK® guide process that formalises the acceptance of deliverables.
In Praxis this is covered by the accept completed work activity in the delivery process and in PRINCE2, by the receive completed work packages activity in Controlling a Stage (CS).

There is no explicit reference to the validation or acceptance of deliverables in ISO21500.


A technique that checks that a product satisfies user requirements.

Validation ensures that the correct product is being developed as opposed to verification which ensures that the solution is being developed correctly.

Validation and verification requirements matrix

A term used by the APM PSMC that encompasses elements of the V life cycle and a requirements traceability matrix.


In value management, value is the ratio of ‘satisfaction of requirements’ over ‘use of resources’.

Value engineering

A technique for generating alternative actions to improve the value of a product by balancing time and cost without affecting the product’s ability to meet user requirements.

Value for money ratio

The ratio of monetary and non-monetary benefits to the investment made to achieve them.

Value management


Value management is concerned with maximising the value of benefits delivered by a project or programme. Since ‘value’ is a subjective term it is important that a balance is maintained between different stakeholder perceptions of what value actually means.

There are many different approaches to the value management procedure but they all follow the same general principles. The technique initially spans the requirements management and solutions development functions but some aspects should be continued through the delivery phase of the life cycle.

Value tree

A diagram that shows the hierarchy of factors that drive value, and the relationships between them.

Variance at completion (VAC)


In earned value management this is the budget at completion less the estimate at completion. A negative result indicates that the project is over budget.


A term used in PRINCE2 product-based planning. This is a variation of a baselined product. For example, if this glossary was a product then an Italian translation would be a variant of that product rather than an entirely different product.

Variation of price contract


A form of fixed price contract where the price is adjusted to take external factors such as increased prices, inflation or deflation into account.

Sometimes referred to as a fixed price with economic price adjustment contract.

Variation order

The term used mainly in the construction and engineering industries for an approved technical change to a project.


Velocity is a measure of performance in an agile project. The velocity is the number of units of work completed in a certain interval. Typically this may be the number of story points completed in each sprint.


A technique that checks that a product meets its acceptance criteria.

Verification ensures that the solution is being developed correctly as opposed to validation which ensures that the correct product is being developed.

Vertical integration

A term used by the APM PSMC to refer to one aspect of the assurance of a project schedule.

This form of schedule assurance confirms that the data at different levels of detail (e.g. within a hierarchy of networks) is consistent and that each network covers the relevant scope.

See also horizontal integration.

Vertical traceability

The GAO SAG term for vertical integration.

Vision statement


A vision statement is a brief description of the end goal of a complex project or programme. The need for a succinct and memorable description is necessary where there are many stakeholders who need to gain an insight into the end result of a complex piece of work.

MSP deals with this in a dedicated theme simply called Vision.


A term used to represent predominantly linear development approaches where (for example) design is completed before development starts and development finishes before testing starts.

Often drawn in a way that graphically resembles a waterfall and usually used to contrast the linear approach to more iterative approaches such as agile.

WBS dictionary

See work breakdown structure dictionary.

Weak matrix


A form of matrix organisation where projects are co-ordinated by people within the functional departments because departmental boundaries do not allow central co-ordination of the project.

Often there is no real project manager with overall responsibility for the management of the project and the co-ordination is likely to be a joint effort between representatives of different departments. This structure is sometimes known as a co-ordination matrix.

Weighted milestone method


An earned value management method that divides a work package into segments so that each segment ends with a milestone. The milestones are then assigned a weighted proportion of the work package costs.

See also earning rules.

What-if analysis

In the days before the widespread use of computers, critical path analysis had to be done by hand. This could take some time and it was unlikely that a planner would repeat the calculation many times in order to test all the questions that start with "What if we tried a different approach?" or "What if that change were to be accepted?"

Computer based scheduling enables many alternatives to be tried with ease in order to test alternative ways of working, the impact of change requests and solutions to problems.

What-if simulation

The performance of a number of analyses (typically those based on a network diagram) according to pre-set parameters, in order to simulate the behaviour of the project under specific varying conditions.

Could be part of a sensitivity analysis.

Whole life cost

The total cost of ownership over the life of an asset. In some cases this is used in a business case rather than just the cost of creating the asset.

Window analysis

The comparison of the baseline schedule and the as-built schedule for a particular period.

Work breakdown code

See breakdown code.

Work breakdown structure (WBS)


A tree diagram that breaks down the project in increasing levels of detail.
Each element of the structure is a product for which acceptance criteria will be defined. The WBS is the basis of the definition of what a project is intended to produce to meet its objectives.

With the use of project planning software the practical application of the WBS has increasingly been to define activities rather than products as the elements within the structure.

This prompted some sources to specify a distinct product breakdown structure or product-based work breakdown structure.

Work breakdown structure dictionary

A term used by the PMBoK® guide, ISO21500 and the APM PSMC for a document that provides detailed deliverable, activity and scheduling information about each component on the work breakdown structure (WBS).

WBS components are similar to work packages in Praxis and PRINCE2 and so the dictionary is the equivalent of a compendium of work package descriptions.

Work calendar

See calendar.

Work package

A package of deliverable work that is sufficiently well defined to allow it to be delegated to a person or team.

Precise definitions vary slightly. For example, the PMBoK® guide defines a work package as being at the lowest level of each branch of a work breakdown structure.

Praxis and PRINCE2 have a broader definition where a work package is a combination of product information together with all the time, cost and other information required to delegate the work.

PRINCE2 goes further and has a formal definition where the work package is ‘the set of information that provides all the information that an individual or team need in order to successfully deliver the component products’. It also confirms agreement between the project manager and individual or team manager that the work can be done within the defined constraints.


A response to an issue that is not a planned response, i.e. as distinct from a pre-determined contingency plan.

A workaround of sufficient size to warrant replanning would result in an exception plan.

Working time

Time measured according to the working week, i.e. in a normal five day week the working time of five days equates to seven days of elapsed time.


An MSP term used to describe a grouping of projects and activities. A workstream may represent a grouping based (for example) on discipline, location or outputs.

Workstreams may cross tranche boundaries and are created to improve the management of related areas of work.

Zero float

A term used when referring to the fact that an activity on the critical path has no float.




14.Feb.2017Updated to version 1.3 including the PMI's standard for program management

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