The following is a list of terms specific to OmniPlan or project management that you’ll encounter throughout this manual, defined and listed in alphabetical order for easy reference.

Actual schedule
The actual schedule, in contrast to the baseline schedule, is the way a project turns out in real life. Before the baseline is set for a project, the baseline and actual schedules are the same. After the baseline is set, further editing changes the actual schedule only.
An attachment is a link to a file somewhere on your computer from inside your OmniPlan project. You can attach files to the project, to a task, or to a resource.
Assigning a resource to a task means that the resource is expected to be actively busy with that task throughout its duration. Assignment amounts are expressed as the percentage of the resource’s time being spent on the task.
Baseline schedule
The baseline schedule, in contrast to the actual schedule, is the way a project is originally planned. Before the baseline is set for a project, the baseline and actual schedules are the same. After the baseline is set, further editing changes the actual schedule only. You can compare the baseline schedule and the actual schedule using the split or both view modes of the Gantt chart.
Calendar View
The mode of the main window in which you can set up working hours and work schedule exceptions for individual resources or for the project as a whole. It contains a replica of the resource outline on the left, and a week view, with green time blocks, on the right.
A member of a group is considered the group’s “child”; this is common terminology for outlining software.
A task or a resource can have a monetary cost. The total cost of a task is the sum of the task cost and the costs of the resources assigned to it. A resource can have a per-use cost and a per-hour cost.
Critical path
The critical path is the series of dependent tasks which, if any of their durations change, will cause the whole project’s duration to change. You can check the critical path from the View menu or the Critical Path toolbar button. Critical paths can be charted to individual milestones as well as to the entire project duration; view a milestone’s critical path by toggling its checkbox in the Milestones inspector.
Custom data
Data you can attach to any project, task, or resource, for your own purposes.
The relationship by which one task must start or finish before another task can start or finish. For example, the task “Buy paint” must finish before the task “Paint fence” can begin.
Duration, in contrast to effort, is how long a task takes to complete in actual working time (that is, not including off-time). For example, a task which takes 4 hours of effort, and is assigned to 2 resources, has a duration of 2 hours. When you assign resources to a task, the duration or effort may change.
The measure of how much work a resource can get done in a certain amount of time. Efficiency can affect duration and effort: 100% efficiency means the resource can contribute 1 hour of effort for every hour of work; 50% efficiency means it can contribute 1 hour of effort for every 2 hours of work; and so on.
Effort, in contrast, to duration, is how much work time a task takes to complete, considering all of the resources assigned to it. For example, a task which has a duration of 4 hours, and has 2 resources assigned to it, has an effort of 8 hours. When you assign resources to a task, the duration or effort may change.
Equipment is a type of resource. It represents some kind of reusable asset, such as some special computer hardware. It can also be useful to consider things like meeting rooms to be “equipment”, if you need to balance their use between different tasks.

For equipment resources, “Units” means how many of the resource are available. The number of available units can affect resource leveling.

Equipment can have Efficiency, Cost per Use, and Cost per Hour values.

Gantt Chart
A Gantt chart is a chronological representation of the project, shown in OmniPlan on the right side of the Task View. Each task is represented by a bar, corresponding to a row in the task outline, and may be connected to other tasks by lines representing dependencies; the horizontal size and position of the bar indicate the expected duration and schedule for the task.
Items in the task outline or the resource outline can be grouped together. The members, or “children”, of the group appear indented from the group itself in the outline. In the Gantt chart, a task group appears as a bracket enclosing its members.
A task of flexible effort whose duration changes based on constraints imposed by tasks scheduled before and after it.
A single row in either the task outline or the resource outline. General outlining commands like Indent and Outdent, Expand and Collapse, work on items in either outline.
Lead Time
Lead time is a duration you can put on a dependency to mean that some amount of time is needed between the two moments involved. For example, a Start→Start dependency with a lead time of 1 day means that after the first task starts, the second task can start one day later.

Lead time can be negative; for instance a Finish→Start dependency with a –2 hour lead time will allow the second task to start once the first task is 2 hours from completion.

You can set up lead time by typing a duration (such as +3w or –2d4h) either at the end of a dependency code in the Dependents or Prerequisites column of the task outline, or in the Task Dependencies inspector.

Lead time can also be a percentage of the predecessor task’s duration; for example you could enter 100% for a lead time just as long as the task it comes after.

“Leveling the project”, or “leveling resources”, means automatically rearranging the project to make sure the resources are being used as efficiently as possible. This means not allowing a resource to be assigned at more than 100% of its available units at any time, and finding the best order for resources to work on tasks in order to complete them more quickly.

Newly created projects are set to automatically level resources as they are allocated to tasks. You can disable automatic leveling in the Project menu.

When not leveling automatically, you should level your project after making changes like updating task completion or changing resource assignments.

Material is a type of resource, representing consumable supplies.

For material resources, “Units” means how many of the resource are being used throughout the project. This value updates as the resource is assigned to more tasks.

Material resources can have Cost per Use and Cost per Hour values.

A milestone is like a task, except that it has no duration and requires no effort. Its purpose is to mark an important point in the project timeline. Based on dependencies and work schedules, a milestone may shift in time; you can keep track of your project’s milestones in Task View and the Milestones inspector.
Monte Carlo Estimation
The Monte Carlo simulation method uses random sampling based on a spread of values to estimate probable outcomes — in the case of OmniPlan Pro, the likelihood that your project or milestone will reach completion on time. When a simulation is run, hundreds of randomized possible outcomes are considered, and the average result is reported as a percentile of confidence that the milestone will be reached on a given day.

Because the estimate data used is randomized across a range of possible values, running multiple Monte Carlo simulations on the same data set will generate slightly different results each time. However, the number of iterations in a single simulation is high enough to eliminate grossly inaccurate outliers.

Network Diagram
A visualization tool that describes a project as a web of task nodes connected by dependencies. Unlike a Gantt chart, a network diagram deemphasizes project chronology in favor of a clear, evident depiction of the relationships between tasks.
A group is considered the “parent” of all its members; this is common terminology for outlining software.
When a project is publishing information about itself, it is telling other projects in a shared server repository what resources assigned to it are up to. If a resource is shared between projects (as indicated by an identifying email address), the load on that resource indicated by all publishing projects is taken into account when leveling across projects subscribing to the repository.
Resources are the people and things needed to get a project done. Resources are listed in the resource outline, and can be assigned to tasks. The three types of resources are Staff, Material, and Equipment.
Resource load / Resource allocation
A resource’s load is the amount of effort it is assigned to do at various times throughout the project. If a resource is assigned at more than 100% of its availability all at once, it is said to be “overloaded” or “overutilized”. Resource leveling tries to alleviate overload of resources. You can see each resource’s load by turning on the resource allocation graphs modeswitcher in the resource timeline.
Resource timeline
On the right side of the resource view is a timeline of the tasks assigned to each resource. It provides a more vertically-compressed, resource-oriented look at the project.
Resource view
The mode of the main window in which you create, edit, and examine resources. It contains the resource outline on the left and the resource timeline on the right.
Also known as float, in project management terminology slack refers to the amount of time a given task can be deferred until its duration to completion conflicts with the beginning of a subsequent dependent task (thereby causing a delay). Free slack refers to slack specific to a task and its successor, while total slack refers to a sum of all free slack in the project up to completion. Both values can be displayed as columns in Task View.
Staff is a type of resource, representing people who work on the project.

Staff units are measured as percentages. A person who is fully available to the project has a units value of 100%; someone who is spending part of their working hours on other projects would have lower available units. Note that this is not the same as having fewer working hours (which can be set in the calendar view), or being less efficient (which can be set in the Resource Info section of the Resource inspector).

Staff can have Address, Efficiency, Cost per Use, and Cost per Hour values.

When a project is subscribing to a shared server repository, it is on the lookout for resource load data being published by other projects. When leveling loads, a subscriber will adjust resources based on usage information received from the published projects.
T day
The first day of a project that has an undetermined start date. Until the start date is set, all dates are represented by an amount of time after T day, such as “T+2w 1d”
Some item of work that needs to be done for the project to progress. A task is represented by a row in the task outline, and by a corresponding task bar in the Gantt chart.
Task View
The mode of the main window in which you create, edit, and examine tasks. It contains the task outline on the left and the Gantt chart on the right.
A template is a file you can use as a starting point for new documents. There are also HTML templates, which are used for creating a web report of a project.
Units measure amounts of resources in various contexts. For a staff resource, the units value is a percentage representing how much of the person’s time is available to be assigned to tasks. For equipment and material resources, the units value is a number representing a physical quantity.
Variance is the amount of time by which the actual date differs from the baseline date.
A violation is some sort of problem in the project that prevents it from working out properly. Such problems are things like tasks that start before the project start date, tasks that don’t have enough time to complete before their dependent tasks need to start, or dependencies that cause a task to be prerequisite to itself.