0 to Ac

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


From 0/100 rule to Actual time expended (ATE)


0/100 rule

See earning rules.

50/50 rule

See earning rules.

Abstract resource

Abstract resources can be introduced into a schedule for computer based resource scheduling. Unlike resources that represent machinery or labour that are needed to perform an activity, abstract resources are introduced purely to provide extra control over the scheduling process.

For example, a resource called ‘space’ could be assigned to activities that are working in a confined space. If two activities run concurrently but, when added together, exceed the stated limit in space, the resource scheduling algorithm will schedule them at different times.


One of the four possible threat responses.

Accept a Work Package

An activity in the Managing Product Delivery (MP) process of PRINCE2.

The purpose of this activity is to ensure that there is agreement between the project manager and team manager on the definition of a work package. This will include performance of risk analysis, agreement of tolerances and inclusion of the work package in the team plan.

The equivalent in Praxis is the accept work package activity in the development process, which works in conjunction with the authorise work activity in the delivery process.

This formal delegation of work from the project manager to a team or individual is not explicit in the PMBoK® guide or ISO21500 but could be considered implicit in the processes Direct and Manage Project Work (PMBoK® guide) and Direct project work (ISO21500).


The formal act of accepting a deliverable according to its pre-defined acceptance criteria. In this context a ‘deliverable’ could constitute a product, work package or project output.

Acceptance criteria

A list of criteria that must be met before a deliverable can pass its acceptance test. The criteria should be measurable so that the deliverable can be verified.

In agile projects these criteria may be referred to as the definition of done for a user story.

Acceptance test

A test used to confirm that acceptance criteria have been achieved.

In Praxis, acceptance tests will typically be performed as part of the deliver products activity in the development process and as part of the handover activity in the closure process.

In PRINCE2, acceptance tests would form part of the deliver a work package and hand over products activities.

In the PMBoK® guide accepted deliverables are an output of the Validate Scope process. ISO21500 does not have an explicit procedure for the acceptance of deliverables.

Accepted deliverables

Products that have been validated by their end users as meeting their acceptance criteria.

Accountability matrix

See responsibility assignment matrix (RAM).


One of the four types of involvement (RACI) in a responsibility assignment matrix.

Someone who is ‘accountable’ is personally answerable for an activity. Unlike responsibility, accountability cannot be delegated.

Accounting rate of return


The accounting rate of return (ARR) is a simple investment appraisal technique for evaluating less complex projects and their benefits.

A key factor that is ignored in ARR is how the value of money changes over time, i.e. in an economy that has price inflation, the value of money earned today is different to the same amount earned in five years’ time. This is taken into account in more sophisticated discounted cash flow methods such as net present value and internal rate of return.


See accrued cost.

Accrued cost

The cost of work that has been done but for which payment is not yet due. For example, if a contractor is performing work valued at £5,000 and payable on completion, and has completed half the work, there is £2,500 of accrued cost.

If the contractor does not complete the work you may not be committed to paying. Once the work is complete according to the contract, but it has not yet been paid, the cost becomes a committed cost.

Acquire Project Team (9.2)

The second process within the PMBoK® guide’s project human resource management knowledge area. It is an executing process that uses the staffing management plan to build the team that will be executing the project. Its main outputs are specific assignments and an updated project management plan.

The corresponding areas of Praxis are the mobilisation function and the process activities where mobilisation is used, i.e. the definition process and boundaries process.

There is no obvious equivalent in PRINCE2 but it could be argued that mobilisation is implicit in the plan the next stage activity in the Managing a Stage Boundary (SB) process.

In ISO21500 the equivalent process is Establish project team.

Action centred leadership

See Adair.


An activity is a piece of work that occurs over a period of time. This is generally used in two ways:

  1. The individual pieces of work that are needed to develop the objectives of a project. These are the building blocks of a network diagram and form the basis of building detailed estimates of the duration, cost and resource requirements of the project.
  2. To describe the components of a process that achieves the goals of a process. This form of the term is used by both Praxis and PRINCE2.

Activity attributes

The attributes of an activity, including information such as dependencies, resource requirements, imposed dates, constraints and assumptions.

Activity box

In a precedence diagram each activity is represented by a box. The activity box is subdivided to provide space for the activity description and the results from a critical path analysis, namely ES (earliest start), D (duration), EF (earliest finish), LS (latest start), F (float) and LF (latest finish).

Activity calendar

In network analysis different activities may have different working patterns, e.g. some activities may only be performed at weekends. All planning software allows the allocation of activity calendars that are used in scheduling to determine the days on which an activity may occur.

See also: calendars.

Activity code

The code given to an activity to ensure it has a unique reference. This can then be used for filtering and ordering activity based reports.

Activity cost estimate

The estimated cost of an activity including all direct costs for resources. Individual activity cost estimates are consolidated in bottom-up estimating to provide detailed estimates for work packages or sections of the work breakdown structure.

Activity description

The description of an activity normally written above the arrow in an activity on arrow diagram or in the centre of the activity box in a precedence diagram.

Activity duration

See duration.

Activity list

This is simply a list of the activities needed to produce the products contained in the work breakdown structure.

While Praxis does not explicitly define an activity list as an output, it is implicit within the identify work activity in the schedule management procedure.  In ISO21500 the activity list is an output of the Define activities process and in the PMBoK® guide it is also an output of the Define Activities process.

In PRINCE2 it is an output of the identifying activities and dependencies step of the planning procedure.

Activity network

See network diagram.

Activity on arrow


The original form of network diagram that has effectively been superseded by the precedence diagram format.

In an activity-on-arrow network, activities are represented by a line between two circles. The first circle represents the start of the activity and is known as the start event (sometimes called the i-node). The second circle represents the finish of the activity and is known as the finish event (sometimes called the j-node).

Activity on node

A form of network diagram in which the activities are represented by nodes and dependencies are represented by arrows. The most common form of activity on node network is the precedence diagram method (PDM).

Activity weeks method

A simple measure of project progress that records the number of activities in progress each week.

Activity-based cost

See activity cost estimate.

Actual cost

The actual money spent in performing an activity so far. The total actual cost may include elements of accrued costs and committed costs.

When used in earned value management this is sometimes referred to as actual cost of work performed (ACWP).

Actual cost of work performed (ACWP)



An earned value management term representing the actual cost of performing an activity, part of a project or the entire project. Some practitioners prefer the simpler term actual cost (AC).

Actual duration

The time that an activity actually took to complete.

Actual effort

The actual time expended by a resource in the performance of an activity.

Actual event time

The time that an event actually occurred in an activity on arrow network.

Actual expenditure

See actual cost.

Actual finish date

The date an activity actually finished.

Actual progress

A measure of the work that has been completed.

Actual start date

The date an activity actually started.

Actual time expended (ATE)

The total time expended on the project to date in earned value management.



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