SCHEDULING

The language of time and sequence—how activities connect, what controls completion, how progress is measured, and how today's field decisions affect what happens next.

ACTIVITY

A defined piece of work in a schedule that has a start, finish, and duration.

Across the Table: In the field, we may call it a task or simply the work. In a schedule, defining it as an activity lets us connect it to other work and track progress.

Use It — Field: “We need to finish setting the cabinets before we start pulling cable.”

Use It — Management: “Cabinet installation is a scheduled activity that must be completed before cable installation can proceed.”

Related: Duration · Predecessor · Successor · Logic

ACTIVITY ID

A unique code used to identify a schedule activity.

Across the Table: The description tells us what the work is. The Activity ID gives that activity a unique reference so everyone can point to the same item without confusion.

Use It — Field: “What's the activity number for the cabinet install?”

Use It — Management: “The cabinet installation is Activity CAB-120 in the current schedule.”

Related: Activity · WBS · Schedule

ACTUAL FINISH

The date an activity was actually completed.

Across the Table: Once an activity has an Actual Finish, we're no longer forecasting when it will end. We're recording what actually happened.

Use It — Field: “We finished that work Tuesday.”

Use It — Management: “The activity has an Actual Finish of Tuesday, August 18.”

Related: Actual Start · Progress Update · Remaining Duration

ACTUAL START

The date an activity actually began.

Across the Table: The planned start tells us when we expected to begin. Actual Start records when work really started.

Use It — Field: “We started that room Monday morning.”

Use It — Management: “The activity has an Actual Start of Monday, August 17.”

Related: Actual Finish · Baseline · Progress Update

BASELINE

An approved snapshot of the schedule used as a reference for comparing current performance against the original or approved plan.

Across the Table: The current schedule can move as the job changes. The baseline preserves the reference point so we can see what changed.

Use It — Field: “We were originally supposed to finish this Friday.”

Use It — Management: “The baseline finish was Friday; the current forecast has moved to next Tuesday.”

Related: Current Schedule · Schedule Variance · Forecast Finish

CALENDAR

The working-time rules assigned to schedule activities, including workdays, hours, holidays, and other nonworking periods.

Across the Table: Two activities with the same duration can finish on different dates if they use different calendars. The calendar tells the schedule when work is actually allowed to occur.

Use It — Field: “That crew doesn't work Sundays, so don't count Sunday as a workday.”

Use It — Management: “This activity uses a six-day calendar, so Sunday is nonworking time.”

Related: Duration · Work Window · Schedule

CPM — CRITICAL PATH METHOD

A scheduling method that uses activity durations and logical relationships to calculate the sequence of work that controls project completion.

Across the Table: CPM turns the field question 'what has to happen next, and what happens if it doesn't?' into schedule logic that can be calculated and analyzed.

Use It — Field: “If this work slips, everything behind it moves with it.”

Use It — Management: “The CPM schedule shows this sequence controlling the current project completion date.”

Related: Critical Path · Logic · Float · Longest Path

CRITICAL ACTIVITY

An activity considered critical under the schedule's defined criticality criteria, commonly because it has little or no available float.

Across the Table: Critical activities deserve attention because delay may threaten important downstream dates. But 'critical' should come from the schedule analysis, not just because the work feels important.

Use It — Field: “We don't have room to let this one slide.”

Use It — Management: “This activity is currently critical and has minimal available float.”

Related: Critical Path · Total Float · Near-Critical

CRITICAL PATH

The sequence of logically connected activities that determines the project's earliest completion under the current schedule.

Across the Table: Not every late activity makes the project late. The critical path identifies the chain of work currently controlling completion.

Use It — Field: “If we lose three days here and don't recover them, the finish date moves.”

Use It — Management: “This activity is on the critical path, so an unrecovered delay can affect project completion.”

Related: CPM · Longest Path · Float · Schedule Risk

CURRENT SCHEDULE

The latest updated version of the schedule reflecting current progress, logic, durations, and known conditions.

Across the Table: The baseline tells us where we started. The current schedule tells us where the job stands now.

Use It — Field: “The old plan said Friday, but with what's happened, we're looking at Tuesday now.”

Use It — Management: “The current schedule forecasts Tuesday completion compared with the Friday baseline.”

Related: Baseline · Progress Update · Forecast Finish

DATA DATE

The point in time that separates recorded progress from remaining scheduled work in a schedule update.

Across the Table: Think of the data date as the schedule's 'as of' date. Work before it should reflect what actually happened; remaining work is calculated forward from it.

Use It — Field: “Everything through Friday needs to be updated before we run the schedule.”

Use It — Management: “This update has a Friday data date, so progress is statused through that point.”

Related: Progress Update · Actual Start · Remaining Duration

DURATION

The amount of working time planned or remaining for an activity, based on the activity's assigned calendar.

Across the Table: Duration is not always the same as elapsed calendar time. A five-day activity means five working days under the calendar assigned to it.

Use It — Field: “This should take the crew about three working days.”

Use It — Management: “The activity has a planned duration of three working days.”

Related: Calendar · Remaining Duration · Activity

EARLY FINISH

The earliest calculated date an activity can finish based on current schedule logic, durations, calendars, and constraints.

Across the Table: Early Finish is what the schedule says is possible if the preceding logic performs as currently modeled.

Use It — Field: “If everything ahead of us goes right, this is the earliest we're getting done.”

Use It — Management: “The activity's current Early Finish is September 10.”

Related: Early Start · Late Finish · Float

EARLY START

The earliest calculated date an activity can start based on current schedule logic, durations, calendars, and constraints.

Across the Table: A desired start date and an Early Start aren't necessarily the same. Early Start is calculated from what must happen before the activity.

Use It — Field: “We want to start Monday, but the schedule says the earliest we can get in is Wednesday.”

Use It — Management: “The activity's Early Start is Wednesday because its predecessor work does not finish until Tuesday.”

Related: Predecessor · Early Finish · Logic

FINISH DATE

The date an activity, milestone, phase, or project is planned, forecast, or actually completed, depending on context.

Across the Table: When somebody says 'the finish date,' ask which one: baseline, current forecast, or actual. They answer different questions.

Use It — Field: “Are we talking about the original finish or where we think we'll finish now?”

Use It — Management: “The baseline finish is October 4; the current forecast finish is October 18.”

Related: Baseline · Forecast Finish · Actual Finish

FINISH-TO-FINISH (FF)

A relationship where the finish of one activity is tied to the finish of another activity.

Across the Table: FF logic is useful when two activities can proceed together but one should not finish until the other reaches its finish point.

Use It — Field: “We can work both at the same time, but final testing can't finish until installation is finished.”

Use It — Management: “Final testing has a Finish-to-Finish relationship with installation.”

Related: Relationship · Logic · Successor · Predecessor

FINISH-TO-START (FS)

A relationship where a successor activity cannot start until its predecessor finishes, subject to any lag or other schedule rules.

Across the Table: This is the relationship field leaders use constantly: finish this before we start that.

Use It — Field: “We can't start cable installation until the cabinets are set.”

Use It — Management: “Cable installation has a Finish-to-Start relationship with cabinet installation.”

Related: Predecessor · Successor · Logic · Lag

FLOAT

Schedule flexibility available before a delay affects another activity or a required completion point. The exact meaning depends on the type of float being discussed.

Across the Table: Float is room in the schedule, not free time to waste. We need to know whether we're talking about total float or free float before making decisions with it.

Use It — Field: “We've got some room here, but I want to know how much before we let this slide.”

Use It — Management: “The activity has available float, but we're verifying whether consuming it affects downstream work or project completion.”

Related: Total Float · Free Float · Critical Path

FORECAST FINISH

The date an activity or project is currently expected to finish based on present progress and schedule conditions.

Across the Table: The baseline finish is where we planned to land. Forecast Finish is where the current information says we're heading.

Use It — Field: “At our current rate, we're finishing Thursday.”

Use It — Management: “Based on current progress, the forecast finish has moved to Thursday.”

Related: Baseline · Current Schedule · Schedule Variance

FREE FLOAT

The amount of time an activity can be delayed without delaying the early start of its immediate successor.

Across the Table: Free float is local flexibility. It tells us how much an activity can move before it begins pushing the next connected activity.

Use It — Field: “We can lose a day here without moving the next crew's start.”

Use It — Management: “This activity has one day of free float before its successor's Early Start is affected.”

Related: Total Float · Successor · Float

LAG

A planned waiting period added to a relationship between two schedule activities.

Across the Table: Lag represents intentional time between connected activities. It should describe a real planning requirement, not hide missing work that should have been modeled as an activity.

Use It — Field: “After the concrete is placed, we need three days before we load it.”

Use It — Management: “The successor has a three-day lag to account for the required cure period.”

Related: Lead · Relationship · Finish-to-Start

LATE FINISH

The latest calculated date an activity can finish without exceeding the schedule's controlling completion requirement, based on the current model.

Across the Table: Late Finish helps show how far an activity can move before it consumes the available schedule flexibility tied to completion.

Use It — Field: “This is about as late as we can finish without hurting the job.”

Use It — Management: “The activity's Late Finish is September 14 under the current schedule calculation.”

Related: Late Start · Total Float · Early Finish

LATE START

The latest calculated date an activity can start without exceeding the schedule's controlling completion requirement, based on the current model.

Across the Table: Late Start is the back edge of the available schedule room under the current logic. Waiting until then leaves little room for another problem.

Use It — Field: “We could start later, but then we've got no cushion left.”

Use It — Management: “The Late Start is Monday; starting after that would create negative impact under the current schedule.”

Related: Late Finish · Total Float · Early Start

LEAD

An overlap that allows a successor to begin before the point normally required by its relationship.

Across the Table: Lead can overlap work, but it needs to reflect how the work can actually be performed. Overlapping activities on paper doesn't make them executable in the field.

Use It — Field: “We don't have to wait for the whole floor to finish; we can start behind them once the first area is ready.”

Use It — Management: “The relationship allows the successor to overlap the predecessor rather than waiting for full completion.”

Related: Lag · Relationship · Fast Tracking

LOGIC

The network of relationships that defines how schedule activities depend on and connect to one another.

Across the Table: Dates alone don't explain a schedule. Logic explains why an activity starts when it does and what moves when something changes.

Use It — Field: “Show me what this task is waiting on and what it holds up behind it.”

Use It — Management: “The schedule logic ties equipment installation to pad completion and makes testing its downstream successor.”

Related: Predecessor · Successor · Relationship · CPM

LONGEST PATH

The continuous path of activities through the schedule that currently determines the project's calculated completion date.

Across the Table: Longest Path is a useful way to identify the chain actually driving completion, especially in CPM tools such as P6.

Use It — Field: “What's the chain of work that actually gets us to the finish?”

Use It — Management: “The longest path currently runs through equipment installation, energization, testing, and turnover.”

Related: Critical Path · CPM · Total Float

LOOK-AHEAD SCHEDULE

A short-term schedule view focused on upcoming work, commonly used to coordinate near-term execution and identify constraints before they reach the field.

Across the Table: The master schedule gives the big picture. The look-ahead gets close enough to the work to ask whether next week is actually ready.

Use It — Field: “Show me the next two weeks and what's going to stop us.”

Use It — Management: “The two-week look-ahead identified access and material constraints that must be cleared before next week's work.”

Related: Readiness · Constraint · Current Schedule

MILESTONE

A significant schedule point used to mark an important event, commitment, completion, or transition, generally with zero duration.

Across the Table: A milestone marks that something important happened or must happen; it isn't the work required to get there.

Use It — Field: “We need the room ready by Friday because that's the turnover date.”

Use It — Management: “Customer turnover is a zero-duration milestone scheduled for Friday.”

Related: Activity · Finish Date · Dependency

NEAR-CRITICAL

An activity or path with limited schedule flexibility that could become critical with relatively little delay or change.

Across the Table: If we only watch today's critical path, we can miss the path that becomes critical tomorrow. Near-critical work deserves attention before the float disappears.

Use It — Field: “This isn't controlling the job yet, but we've only got a couple days of room.”

Use It — Management: “This path is near-critical with two days of total float and should be monitored closely.”

Related: Critical Activity · Total Float · Schedule Risk

NEGATIVE FLOAT

A calculated condition where the schedule indicates that a required or constrained completion date cannot be met under the current logic, durations, calendars, and constraints.

Across the Table: Negative float is the schedule telling us the current plan does not support the required date. It isn't a recovery plan by itself; it is a warning that something has to change.

Use It — Field: “The schedule is telling us we're already past the room we had.”

Use It — Management: “The update shows three days of negative float against the required completion date, so recovery action is needed.”

Related: Total Float · Recovery Schedule · Schedule Compression

OPEN END

An activity missing a logical predecessor, successor, or both, leaving part of the schedule network disconnected.

Across the Table: An open end can make an activity float without a realistic connection to what drives it or what it drives. If the work really depends on something, the schedule should show it.

Use It — Field: “This task can't just happen whenever. What has to happen before it, and what does it hold up?”

Use It — Management: “This activity has an open end and needs appropriate logic before we rely on its calculated dates.”

Related: Logic · Predecessor · Successor · CPM

OUT-OF-SEQUENCE PROGRESS

Progress recorded on an activity in a way that does not follow the logic currently modeled in the schedule.

Across the Table: The field sometimes finds a legitimate way to work ahead of the schedule logic. When that happens, the scheduler needs to understand whether the logic is wrong, the execution changed, or the update needs different treatment.

Use It — Field: “We started this early because the area opened up even though the schedule had us waiting.”

Use It — Management: “The update shows out-of-sequence progress; we need to verify whether the field sequence changed and whether the schedule logic should be revised.”

Related: Logic · Resequencing · Progress Update

PERCENT COMPLETE

A measure of how much of an activity is considered complete. The exact calculation can depend on the schedule system and the type of percent complete being used.

Across the Table: 'Half done' can mean different things depending on whether we're measuring duration, physical work, or units. The basis needs to be understood before relying on the number.

Use It — Field: “We've installed five of the ten units, so physically we're about halfway done.”

Use It — Management: “The activity is reporting 50 percent physical completion based on installed quantities.”

Related: Progress Update · Remaining Duration · Actual vs. Planned

PREDECESSOR

An activity that comes before another activity in the schedule network and is connected to it by a logical relationship.

Across the Table: It's the scheduling version of asking: what does this work depend on before it can move?

Use It — Field: “We can't set the equipment until the pad is finished.”

Use It — Management: “Pad completion is the predecessor to equipment installation.”

Related: Successor · Dependency · Logic · Finish-to-Start

PROGRESS UPDATE

The process of recording actual starts, finishes, remaining durations, percent complete, and other current information so the schedule reflects project status as of the data date.

Across the Table: A schedule update should tell the truth about the field, not force the field to match last month's plan.

Use It — Field: “We started this Monday, finished that Tuesday, and this one has two days left.”

Use It — Management: “The progress update records actual status through the data date and recalculates the remaining schedule.”

Related: Data Date · Actual Start · Actual Finish · Remaining Duration

RELATIONSHIP

The logical connection between two schedule activities that defines how the timing of one affects the other.

Across the Table: Relationships are how the schedule models sequencing. The common types are Finish-to-Start, Start-to-Start, Finish-to-Finish, and Start-to-Finish.

Use It — Field: “Tell me how these two tasks are tied together.”

Use It — Management: “These activities are connected by a Finish-to-Start relationship.”

Related: Logic · Predecessor · Successor · Lag

REMAINING DURATION

The amount of working time currently estimated to be needed to finish an activity that has not yet been completed.

Across the Table: Once work starts, the original duration matters less than an honest estimate of what is still left.

Use It — Field: “We started it, but we've still got about two days of work left.”

Use It — Management: “The activity has two working days of remaining duration as of the data date.”

Related: Duration · Progress Update · Forecast Finish

RESEQUENCING

Changing the planned order of work because conditions, priorities, constraints, or opportunities have changed.

Across the Table: Resequencing can keep crews productive, but the schedule should reflect the new execution path if the change affects logic or downstream work.

Use It — Field: “Electrical isn't ready, so we're moving outside and coming back to this room later.”

Use It — Management: “We're resequencing around the electrical constraint and updating the affected schedule logic.”

Related: Logic · Constraint · Out-of-Sequence Progress

RESOURCE LOADING

Assigning labor, equipment, or other resources to schedule activities so resource demand can be evaluated over time.

Across the Table: A schedule can show two crews working at once even when we only own one crew. Resource loading exposes that mismatch.

Use It — Field: “The schedule has both sites starting Monday, but I've only got one crew.”

Use It — Management: “Resource loading shows concurrent demand for two crews while only one is available.”

Related: Capacity · Leveling · Activity

SCHEDULE COMPRESSION

Shortening the planned project duration without reducing the required scope, typically by changing sequencing, adding resources, or both.

Across the Table: Compression means finding a credible way to finish sooner. Simply changing the finish date on the schedule is not compression.

Use It — Field: “If we need this a week earlier, something about how we're doing the work has to change.”

Use It — Management: “We're evaluating schedule compression through parallel work and additional resources.”

Related: Fast Tracking · Crashing · Recovery Schedule

SCHEDULE LOGIC

The complete set of activity relationships that represents the intended sequence and dependencies of the work.

Across the Table: Good schedule logic should resemble how the job can actually be built. Bad logic can produce dates that look precise but mean very little.

Use It — Field: “If the schedule says we can test before power is available, the logic is wrong.”

Use It — Management: “We're reviewing schedule logic to confirm it reflects the actual construction sequence and prerequisites.”

Related: Logic · CPM · Open End · Dependency

SCHEDULE RISK

A condition or uncertainty that could cause an activity, milestone, or project completion to occur later than planned.

Across the Table: A schedule risk is not necessarily a delay yet. It is something that can become a delay if we don't manage it.

Use It — Field: “If that switchgear slips another week, we're going to lose our start date.”

Use It — Management: “Switchgear delivery is a schedule risk to the planned energization milestone.”

Related: Mitigation · Critical Path · Constraint

SCHEDULE VARIANCE

A difference between planned or baseline schedule performance and current or actual performance.

Across the Table: Variance tells us that the plan and reality have separated. It does not, by itself, tell us why or what to do next.

Use It — Field: “We planned to be done Friday, and now we're looking at Tuesday.”

Use It — Management: “The current forecast shows a four-day variance from the baseline finish.”

Related: Baseline · Forecast Finish · Root Cause

START-TO-FINISH (SF)

A relationship where the finish of a successor is tied to the start of its predecessor. It is uncommon in typical construction schedules.

Across the Table: This relationship is rare. If it appears, understand why it is being used rather than assuming it behaves like the more common Finish-to-Start relationship.

Use It — Field: “I don't see this relationship often; explain what event has to start before the other work can finish.”

Use It — Management: “This Start-to-Finish relationship should be reviewed to confirm it represents the intended execution logic.”

Related: Relationship · Logic · Finish-to-Start

START-TO-START (SS)

A relationship where the start of a successor is tied to the start of its predecessor, subject to any lag or other schedule rules.

Across the Table: The activities can overlap, but the successor cannot start until the predecessor has started as defined by the relationship.

Use It — Field: “Once the first crew starts cable tray, the second crew can start pulling behind them.”

Use It — Management: “Cable pulling has a Start-to-Start relationship with tray installation.”

Related: Relationship · Lead · Lag · Fast Tracking

SUCCESSOR

An activity that follows another activity in the schedule network and is connected to it by a logical relationship.

Across the Table: It's the scheduling version of asking: what work is waiting on this to happen?

Use It — Field: “Once we finish this room, testing can start.”

Use It — Management: “Testing is the successor to equipment installation.”

Related: Predecessor · Dependency · Logic · Finish-to-Start

TOTAL FLOAT

The amount of time an activity can be delayed before it affects the schedule's controlling completion requirement, based on the current schedule calculation.

Across the Table: Total float is schedule flexibility, but it belongs to the network, not to one person or trade as spare time to spend casually.

Use It — Field: “We've got two days of room here before this starts hurting the finish.”

Use It — Management: “The activity currently has two days of total float before the controlling completion date is affected.”

Related: Free Float · Critical Path · Negative Float

WBS — WORK BREAKDOWN STRUCTURE

A hierarchical way of organizing project scope and schedule activities into manageable sections or levels.

Across the Table: The WBS is the filing structure of the schedule. It helps group the work by project, phase, area, system, or another useful breakdown.

Use It — Field: “Put all the equipment-room activities together so we can see that part of the job.”

Use It — Management: “The equipment-room activities are grouped under the corresponding WBS element.”

Related: Activity · Work Package · Schedule

CRASHING

A schedule-compression technique that adds resources or cost to critical work in an effort to shorten its duration.

Across the Table: Crashing means spending more or applying more resources where it can actually buy time. Adding people to noncritical work does not recover the finish date.

Use It — Field: “If another crew can really cut three days off this critical work, let's price it.”

Use It — Management: “We're evaluating crashing the critical activity by adding a second crew and comparing the cost against the time recovered.”

Related: Schedule Compression · Critical Path · Resource Loading

FAST TRACKING

A schedule-compression technique that overlaps activities that were originally planned more sequentially, increasing execution risk in exchange for potential time savings.

Across the Table: Fast tracking is doing work in parallel that we would normally do one after another. It can save time, but it can also create rework, congestion, and coordination risk.

Use It — Field: “We're going to start the next area before this one is completely finished.”

Use It — Management: “We're fast tracking the work by overlapping installation activities to recover schedule time.”

Related: Schedule Compression · Start-to-Start · Risk Assessment

LEVELING

Adjusting activity timing to resolve resource demand that exceeds the resources actually available.

Across the Table: If the schedule wants the same crew or equipment in two places at once, something has to move. Leveling makes the plan fit the resources.

Use It — Field: “I've only got one crane, so these lifts can't both happen Tuesday.”

Use It — Management: “We're leveling the schedule around the single available crane.”

Related: Resource Loading · Capacity · Resequencing

CONSTRAINT

A restriction applied to an activity or milestone that limits when it can start or finish, or a real-world condition that limits execution. In scheduling, the exact meaning depends on whether we mean a schedule constraint or a field constraint.

Across the Table: Field leaders use constraint broadly for anything blocking work. In CPM software, a constraint can also be a specific date restriction that affects schedule calculations.

Use It — Field: “We can't start until the outage is approved.”

Use It — Management: “The outage approval is a field constraint; any imposed date constraint in the schedule should also be reviewed for its effect on logic and float.”

Related: Schedule Risk · Logic · Total Float